1.
88 modern constellations by area
–
The table below ranks the 88 modern constellations by the solid angle that they subtend in the sky, measured in square degrees and millisteradians. Before Delportes work, there was no standard list of the boundaries of each constellation and this skew will increase over the years and centuries to come. However, this does not change the angle of any constellation
88 modern constellations by area
–
Hydra is the largest constellation.
2.
Constellation
–
A constellation is formally defined as a region of the celestial sphere, with boundaries laid down by the International Astronomical Union. The constellation areas mostly had their origins in Western-traditional patterns of stars from which the constellations take their names, in 1922, the International Astronomical Union officially recognized the 88 modern constellations, which cover the entire sky. They began as the 48 classical Greek constellations laid down by Ptolemy in the Almagest, Constellations in the far southern sky are late 16th- and mid 18th-century constructions. 12 of the 88 constellations compose the zodiac signs, though the positions of the constellations only loosely match the dates assigned to them in astrology. The term constellation can refer to the stars within the boundaries of that constellation. Notable groupings of stars that do not form a constellation are called asterisms, when astronomers say something is “in” a given constellation they mean it is within those official boundaries. Any given point in a coordinate system can unambiguously be assigned to a single constellation. Many astronomical naming systems give the constellation in which an object is found along with a designation in order to convey a rough idea in which part of the sky it is located. For example, the Flamsteed designation for bright stars consists of a number, the word constellation seems to come from the Late Latin term cōnstellātiō, which can be translated as set of stars, and came into use in English during the 14th century. It also denotes 88 named groups of stars in the shape of stellar-patterns, the Ancient Greek word for constellation was ἄστρον. Colloquial usage does not draw a distinction between constellation in the sense of an asterism and constellation in the sense of an area surrounding an asterism. The modern system of constellations used in astronomy employs the latter concept, the term circumpolar constellation is used for any constellation that, from a particular latitude on Earth, never sets below the horizon. From the North Pole or South Pole, all constellations south or north of the equator are circumpolar constellations. In the equatorial or temperate latitudes, the term equatorial constellation has sometimes been used for constellations that lie to the opposite the circumpolar constellations. They generally include all constellations that intersect the celestial equator or part of the zodiac, usually the only thing the stars in a constellation have in common is that they appear near each other in the sky when viewed from the Earth. In galactic space, the stars of a constellation usually lie at a variety of distances, since stars also travel on their own orbits through the Milky Way, the star patterns of the constellations change slowly over time. After tens to hundreds of thousands of years, their familiar outlines will become unrecognisable, the terms chosen for the constellation themselves, together with the appearance of a constellation, may reveal where and when its constellation makers lived. The earliest direct evidence for the constellations comes from inscribed stones and it seems that the bulk of the Mesopotamian constellations were created within a relatively short interval from around 1300 to 1000 BC
Constellation
Constellation
Constellation
–
Babylonian tablet recording Halley's comet in 164 BC.
Constellation
–
Chinese star map with a cylindrical projection (Su Song)
3.
Exoplanet
–
An exoplanet or extrasolar planet is a planet that orbits a star other than the Sun. The first scientific detection of an exoplanet was in 1988, HARPS has discovered about a hundred exoplanets while the Kepler space telescope has found more than two thousand. Kepler has also detected a few thousand candidate planets, of which about 11% may be false positives, on average, there is at least one planet per star, with a percentage having multiple planets. About 1 in 5 Sun-like stars have an Earth-sized planet in the habitable zone, the least massive planet known is Draugr, which is about twice the mass of the Moon. There are planets that are so near to their star that they take only a few hours to orbit, some are so far out that it is difficult to tell whether they are gravitationally bound to the star. Almost all of the planets detected so far are within the Milky Way, the nearest exoplanet is Proxima Centauri b, located 4.2 light-years from Earth and orbiting Proxima Centauri, the closest star to the Sun. The discovery of exoplanets has intensified interest in the search for extraterrestrial life, there is special interest in planets that orbit in a stars habitable zone, where it is possible for liquid water, a prerequisite for life on Earth, to exist on the surface. The study of planetary habitability also considers a range of other factors in determining the suitability of a planet for hosting life. The rogue planets in the Milky Way possibly number in the billions, the convention for designating exoplanets is an extension of the system used for designating multiple-star systems as adopted by the International Astronomical Union. For exoplanets orbiting a star, the designation is normally formed by taking the name or, more commonly, designation of its parent star. The first planet discovered in a system is given the designation b, if several planets in the same system are discovered at the same time, the closest one to the star gets the next letter, followed by the other planets in order of orbital size. A provisional IAU-sanctioned standard exists to accommodate the designation of circumbinary planets, a limited number of exoplanets have IAU-sanctioned proper names. Various detection claims made in the century were rejected by astronomers. The first scientific detection of an exoplanet began in 1988, However, the first confirmed detection came in 1992, with the discovery of several terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a star was made in 1995. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method, in the eighteenth century the same possibility was mentioned by Isaac Newton in the General Scholium that concludes his Principia. Claims of exoplanet detections have been made since the nineteenth century, some of the earliest involve the binary star 70 Ophiuchi. In 1855 William Stephen Jacob at the East India Companys Madras Observatory reported that orbital anomalies made it highly probable that there was a body in this system
Exoplanet
–
Artist's view gives an impression of how commonly planets orbit the stars in the Milky Way.
Exoplanet
–
The three known planets of the star HR8799, as imaged by the Hale Telescope. The light from the central star was blanked out by a vector vortex coronagraph.
Exoplanet
–
2MASS J044144 is a brown dwarf with a companion about 5–10 times the mass of Jupiter. It is not clear whether this companion object is a sub-brown dwarf or a planet.
Exoplanet
–
Coronagraphic image of AB Pictoris showing a companion (bottom left), which is either a brown dwarf or a massive planet. The data was obtained on 16 March 2003 with NACO on the VLT, using a 1.4 arcsec occulting mask on top of AB Pictoris.
4.
Polaris
–
Polaris, designated Alpha Ursae Minoris, commonly the North Star or Pole Star, is the brightest star in the constellation of Ursa Minor. It is very close to the celestial pole, making it the current northern pole star. The revised Hipparcos parallax gives a distance to Polaris of about 433 light-years, Polaris is a multiple star, comprising the main star in orbit with a smaller companion, the pair in orbit with Polaris B. There were once thought to be two more distant components—Polaris C and Polaris D—but these have been not to be physically associated with the Polaris system. Polaris Aa is a 4.5 solar mass F7 yellow supergiant of spectral type Ib and this is the first classical Cepheid to have a mass determined from its orbit. William Herschel discovered the star in 1780 while using a hand-built reflecting telescope, in 1929 it was discovered, by examining the spectrum of Polaris A, that it was a very close binary, with the secondary being a dwarf, which had been theorized in earlier observations. In January 2006, NASA released images, from the Hubble telescope, that showed the three members of the Polaris ternary system. The nearest dwarf star is in an orbit of only 18.5 au from Polaris A, about the distance between the Sun and Uranus), which explains why its light is swamped by its close and much brighter companion. Polaris A, the supergiant primary component, is a low-amplitude Population I classical Cepheid variable, cepheids constitute an important standard candle for determining distance, so Polaris, as the closest such star, is heavily studied. The variability of Polaris had been suspected since 1852, this variation was confirmed by Ejnar Hertzsprung in 1911, the range of brightness of Polaris during its pulsations is given as 1. 86–2.13, but the amplitude has changed since discovery. Prior to 1963, the amplitude was over 0.1 magnitude and was gradually decreasing. After 1966 it very rapidly decreased until it was less than 0.05 magnitude, since then and it has been reported that the amplitude is now increasing again, a reversal not seen in any other Cepheid. The period, roughly 4 days, has changed over time. It has steadily increased by around 4.5 seconds per year except for a hiatus in 1963–1965 and this was originally thought to be due to secular redward evolution across the Cepheid instability strip, but it may be due to interference between the primary and the first-overtone pulsation modes. Authors disagree on whether Polaris is a fundamental or first-overtone pulsator, the temperature of Polaris varies by only a small amount during its pulsations, but the amount of this variation is variable and unpredictable. The erratic changes of temperature and the amplitude of changes during each cycle, from less than 50 K to at least 170 K. Research reported in Science suggests that Polaris is 2.5 times brighter today than when Ptolemy observed it, because of its importance in celestial navigation, Polaris is known by numerous names. It became known as Polaris during the Renaissance, its derived from the Latin polaris of/near the pole
Polaris
–
Polaris as seen by the Hubble Space Telescope.
Polaris
–
This artist's concept shows three class F stars: supergiant Polaris A, dwarf Polaris Ab, and its distant dwarf companion, Polaris B
Polaris
–
A typical Northern Hemisphere star trail with Polaris in the center
Polaris
–
Ursa Major and Ursa Minor in relation to Polaris
5.
Camelopardalis
–
Camelopardalis /kəˌmɛləˈpɑːrdəlᵻs/ or the Giraffe constellation is a large, faint grouping of stars in the northern sky. The constellation was introduced in 1612 by Petrus Plancius, some older astronomy books give an alternative spelling of the name, Camelopardalus, Camelopardi as well as Camelopardus. Although Camelopardalis is the 18th largest constellation, it is not a bright constellation. In fact, it contains four stars below magnitude 5.0. α Cam is a supergiant star of magnitude 4.3,5000 light-years from Earth. It is one of the most distant stars easily visible with the naked eye, β Cam is the brightest star in Camelopardalis with an apparent magnitude of 4.03. This star is a star, with components of magnitudes 4.0 and 8.6. The primary is a yellow-hued supergiant 1000 light-years from Earth,11 Cam is a star of magnitude 5.2,650 light-years from Earth. It is very close to magnitude 6.112 Cam, also 650 light-years from Earth, Σ1694 is a binary star 300 light-years from Earth. Both components have a hue, the primary is of magnitude 5.4. CS Cam is the second brightest star, though it has neither a Bayer nor a Flamsteed designation and it is of magnitude 4.21 and is slightly variable. Z Cam is frequently observed as part of a program of AAVSO and it is the prototype of Z Camelopardalis variable stars. Other variable stars are U Camelopardalis, VZ Camelopardalis, and Mira variables T Camelopardalis, X Camelopardalis, RU Camelopardalis is one of the brighter Type II Cepheids visible in the night sky. In 2011 a supernova was discovered in the constellation, Camelopardalis is in the part of the celestial sphere facing away from the galactic plane. Accordingly, many distant galaxies are visible within its borders, NGC2403 is a galaxy in the M81 group of galaxies, located approximately 12 million light-years from Earth with a redshift of 0.00043. It is classified as being between an elliptical and a spiral galaxy because it has faint arms and a central bulge. NGC2403 was first discovered by the 18th century astronomer William Herschel and it has an integrated magnitude of 8.0 and is approximately 0. 25° long. NGC1502 is a magnitude 6.9 open cluster about 3,000 light years from Earth and it has about 45 bright members, and features a double star of magnitude 7.0 at its center
Camelopardalis
–
The constellation Camelopardalis as it can be seen by the naked eye.
Camelopardalis
–
List of stars in Camelopardalis
Camelopardalis
–
Camelopardalis as depicted in Urania's Mirror, a set of constellation cards published in London c.1825. Above it are shown the now-abandoned constellations of Tarandus and Custos Messium.
6.
Cepheus (constellation)
–
Cepheus is a constellation in the northern sky. It is named after Cepheus, King of Aethiopia in Greek mythology and it was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest star is Alpha Cephei with an apparent magnitude of 3.5, Delta Cephei is the prototype of an important class of star known as a Cepheid variable. RW Cephei, an orange hypergiant, together with the red supergiants Mu Cephei, VV Cephei, Cepheus was the King of Aethiopia. He was married to Cassiopeia and was the father of Andromeda, Delta Cephei is the prototype Cepheid variable, a yellow-hued supergiant star 980 light-years from Earth. It was discovered to be variable by John Goodricke in 1784 and it varies between 3. 5m and 4. 4m over a period of 5 days and 9 hours. The Cepheids are a class of pulsating variable stars, Delta Cephei has a size of 40 solar diameters. It is also a star, the yellow star also has a wide-set blue-hued companion of magnitude 6.3. There are several other prominent variable stars in Cepheus, one, μ Cephei, is also known as Herschels Garnet Star due to its deep red colour. It is a variable star with a minimum magnitude of 5.1. Its period is approximately 2 years, the star is around 11.8 AU in radius. If it were placed at the center of the Solar System, another, VV Cephei A, like Mu Cephei, is a red supergiant and a semiregular variable star, located at least 5,000 light-years from Earth. It has a magnitude of 5.4 and a maximum magnitude of 4.8. One of the largest stars in the galaxy, it has a diameter of 1,300 solar diameters. VV Cephei is also an unusually long-period eclipsing binary, but the eclipses, T Cephei, also a red giant, is a Mira variable with a minimum magnitude of 11.3 and a maximum magnitude of 5.2,685 light-years from Earth. It has a period of 13 months and a diameter of 500 solar diameters, there are several prominent double stars and binary stars in Cepheus. Omicron Cephei is a star with a period of 800 years. The system,211 light-years from Earth, consists of an orange-hued giant primary of magnitude 4.9, xi Cephei is another binary star,102 light-years from Earth, with a period of 4000 years
Cepheus (constellation)
–
The constellation Cepheus as it can be seen by the naked eye.
Cepheus (constellation)
–
List of stars in Cepheus
Cepheus (constellation)
–
NGC 7354 is a planetary nebula located in the constellation Cepheus.
Cepheus (constellation)
–
Cepheus as depicted in Urania's Mirror, a set of constellation cards published in London c. 1825.
7.
North Pole
–
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is defined as the point in the Northern Hemisphere where the Earths axis of rotation meets its surface. The North Pole is the northernmost point on the Earth, lying diametrically opposite the South Pole and it defines geodetic latitude 90° North, as well as the direction of true north. At the North Pole all directions point south, all lines of longitude converge there, along tight latitude circles, counterclockwise is east and clockwise is west. The North Pole is at the center of the Northern Hemisphere, while the South Pole lies on a continental land mass, the North Pole is located in the middle of the Arctic Ocean amid waters that are almost permanently covered with constantly shifting sea ice. This makes it impractical to construct a permanent station at the North Pole, however, the Soviet Union, and later Russia, constructed a number of manned drifting stations on a generally annual basis since 1937, some of which have passed over or very close to the Pole. Since 2002, the Russians have also established a base, Barneo. This operates for a few weeks during early spring, studies in the 2000s predicted that the North Pole may become seasonally ice-free because of Arctic ice shrinkage, with timescales varying from 2016 to the late 21st century or later. The sea depth at the North Pole has been measured at 4,261 m by the Russian Mir submersible in 2007 and at 4,087 m by USS Nautilus in 1958. The nearest land is said to be Kaffeklubben Island, off the northern coast of Greenland about 700 km away. The nearest permanently inhabited place is Alert in the Qikiqtaaluk Region, Nunavut, Canada, around the beginning of the 20th century astronomers noticed a small apparent variation of latitude, as determined for a fixed point on Earth from the observation of stars. Part of this variation could be attributed to a wandering of the Pole across the Earths surface, the wandering has several periodic components and an irregular component. The component with a period of about 435 days is identified with the eight-month wandering predicted by Euler and is now called the Chandler wobble after its discoverer and it is desirable to tie the system of Earth coordinates to fixed landforms. Of course, given plate tectonics and isostasy, there is no system in all geographic features are fixed. Yet the International Earth Rotation and Reference Systems Service and the International Astronomical Union have defined a framework called the International Terrestrial Reference System. As early as the 16th century, many eminent people correctly believed that the North Pole was in a sea and it was therefore hoped that passage could be found through ice floes at favorable times of the year. Several expeditions set out to find the way, generally with whaling ships, one of the earliest expeditions to set out with the explicit intention of reaching the North Pole was that of British naval officer William Edward Parry, who in 1827 reached latitude 82°45′ North. In 1871 the Polaris expedition, a US attempt on the Pole led by Charles Francis Hall, another British Royal Navy attempt on the pole, part of the British Arctic Expedition, by Commander Albert H. Markham reached a then-record 83°2026 North in May 1876 before turning back. An 1879–1881 expedition commanded by US naval officer George W. DeLong ended tragically when their ship, over half the crew, including DeLong, were lost
North Pole
–
North Pole scenery
North Pole
–
An Azimuthal projection showing the Arctic Ocean and the North Pole. The map also shows the 75th parallel north and 60th parallel north.
North Pole
–
Gerardus Mercator 's map of the North Pole from 1595
North Pole
–
C.G. Zorgdragers map of the North Pole from 1720
8.
Ursa Major
–
Ursa Major is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by Ptolemy, it one of the 88 modern constellations. It can be throughout the year in most of the northern hemisphere. The Big Dipper and the constellation as a whole have mythological significance in world cultures. Ursa Major occupies an area in the northern celestial hemisphere. Its also the namesake of its family, which includes all the constellations it borders except for Leo. The three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is UMa, the Big Dipper is an asterism within Ursa Major composed of seven bright stars that together comprise one of the best-known patterns in the sky. β Ursae Majoris, called Merak, with a magnitude of 2.37, γ Ursae Majoris, known as either Phecda or Phad, with a magnitude of 2.44. δ Ursae Majoris, or Megrez, meaning root of the tail, Alioth is the brightest star of Ursa Major and the 33rd-brightest in the sky, with a magnitude of 1.76. It is also the brightest of the peculiar A stars, magnetic stars whose chemical elements are either depleted or enhanced, ζ Ursae Majoris, Mizar, the second star in from the end of the handle of the Big Dipper, and the constellations fourth-brightest star. Mizar, which means girdle, forms a double star, with its optical companion Alcor. The ability to resolve the two stars with the eye is often quoted as a test of eyesight, although even people with quite poor eyesight can see the two stars. η Ursae Majoris, known as either Alkaid or Benetnash, both meaning the end of the tail, with a magnitude of 1.85, Alkaid is the third-brightest star of Ursa Major. Except for Dubhe and Alkaid, the stars of the Big Dipper all have proper motions heading toward a point in Sagittarius. A few other such stars have been identified, and together they are called the Ursa Major Moving Group, the stars Merak and Dubhe are known as the pointer stars because they are helpful for finding Polaris, also known as the North Star or Pole Star. By visually tracing a line from Merak through Dubhe and continuing, ones eye will land on Polaris, W Ursae Majoris is the prototype of a class of contact binary variable stars, and ranges between 7. 75m and 8. 48m. 47 Ursae Majoris is a Sun-like star with a three-planet system,47 Ursae Majoris b, discovered in 1996, orbits every 1078 days and is 2.53 times the mass of Jupiter. 47 Ursae Majoris c, discovered in 2001, orbits every 2391 days and is 0.54 times the mass of Jupiter
Ursa Major
–
Visible at latitudes between + 90 ° and − 30 °. Best visible at 21:00 (9 p.m.) during the month of April. The Big Dipper or Plough.
Ursa Major
–
List of stars in Ursa Major
Ursa Major
–
The constellation Ursa Major as it can be seen by the unaided eye.
Ursa Major
–
Ursa Major and Ursa Minor in relation to Polaris
9.
Ptolemy
–
Claudius Ptolemy was a Greek writer, known as a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in the city of Alexandria in the Roman province of Egypt, wrote in Koine Greek, beyond that, few reliable details of his life are known. His birthplace has been given as Ptolemais Hermiou in the Thebaid in a statement by the 14th-century astronomer Theodore Meliteniotes. This is a very late attestation, however, and there is no reason to suppose that he ever lived elsewhere than Alexandria. Ptolemy wrote several treatises, three of which were of importance to later Byzantine, Islamic and European science. The first is the astronomical treatise now known as the Almagest, although it was entitled the Mathematical Treatise. The second is the Geography, which is a discussion of the geographic knowledge of the Greco-Roman world. The third is the treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day. This is sometimes known as the Apotelesmatika but more known as the Tetrabiblos from the Greek meaning Four Books or by the Latin Quadripartitum. The name Claudius is a Roman nomen, the fact that Ptolemy bore it indicates he lived under the Roman rule of Egypt with the privileges and political rights of Roman citizenship. It would have suited custom if the first of Ptolemys family to become a citizen took the nomen from a Roman called Claudius who was responsible for granting citizenship, if, as was common, this was the emperor, citizenship would have been granted between AD41 and 68. The astronomer would also have had a praenomen, which remains unknown and it occurs once in Greek mythology, and is of Homeric form. All the kings after him, until Egypt became a Roman province in 30 BC, were also Ptolemies, abu Mashar recorded a belief that a different member of this royal line composed the book on astrology and attributed it to Ptolemy. The correct answer is not known”, Ptolemy wrote in Greek and can be shown to have utilized Babylonian astronomical data. He was a Roman citizen, but most scholars conclude that Ptolemy was ethnically Greek and he was often known in later Arabic sources as the Upper Egyptian, suggesting he may have had origins in southern Egypt. Later Arabic astronomers, geographers and physicists referred to him by his name in Arabic, Ptolemys Almagest is the only surviving comprehensive ancient treatise on astronomy. Ptolemy presented his models in convenient tables, which could be used to compute the future or past position of the planets. The Almagest also contains a catalogue, which is a version of a catalogue created by Hipparchus
Ptolemy
–
Engraving of a crowned Ptolemy being guided by the muse Astronomy, from Margarita Philosophica by Gregor Reisch, 1508. Although Abu Ma'shar believed Ptolemy to be one of the Ptolemies who ruled Egypt after the conquest of Alexander the title ‘King Ptolemy’ is generally viewed as a mark of respect for Ptolemy's elevated standing in science.
Ptolemy
–
Early Baroque artist's rendition
Ptolemy
–
A 15th-century manuscript copy of the Ptolemy world map, reconstituted from Ptolemy's Geography (circa 150), indicating the countries of " Serica " and "Sinae" (China) at the extreme east, beyond the island of "Taprobane" (Sri Lanka, oversized) and the "Aurea Chersonesus" (Malay Peninsula).
Ptolemy
–
Prima Europe tabula. A C15th copy of Ptolemy's map of Britain
10.
Star
–
It is primarily present in steroid-producing cells, including theca cells and luteal cells in the ovary, Leydig cells in the testis and cell types in the adrenal cortex. The aqueous phase between two membranes cannot be crossed by the lipophilic cholesterol, unless certain proteins assist in this process. It is now clear that this process is mediated by the action of StAR. The mechanism by which StAR causes cholesterol movement remains unclear as it appears to act from the outside of the mitochondria, some involve StAR transferring cholesterol itself like a shuttle. Another notion is that it causes cholesterol to be kicked out of the membrane to the inner. StAR may also promote the formation of contact sites between the outer and inner mitochondrial membranes to allow cholesterol influx, another suggests that StAR acts in conjunction with PBR, causing the movement of Cl− out of the mitochondria to facilitate contact site formation. However, evidence for an interaction between StAR and PBR remains elusive, in humans, the gene for StAR is located on chromosome 8p11.2 and the protein has 285 amino acids. The signal sequence of StAR that targets it to the mitochondria is clipped off in two steps with import into the mitochondria, phosphorylation at the serine at position 195 increases its activity. The domain of StAR important for promoting cholesterol transfer is the StAR-related transfer domain, StAR is the prototypic member of the START domain family of proteins and is thus also known as STARD1 for START domain-containing protein 1. It is hypothesized that the START domain forms a pocket in StAR that binds single cholesterol molecules for delivery to P450scc, the closest homolog to StAR is MLN64. Together they comprise the StarD1/D3 subfamily of START domain-containing proteins, StAR is a mitochondrial protein that is rapidly synthesized in response to stimulation of the cell to produce steroid. Hormones that stimulate its production depend on the type and include luteinizing hormone, ACTH. At the cellular level, StAR is synthesized typically in response to activation of the second messenger system. StAR has thus far found in all tissues that can produce steroids, including the adrenal cortex, the gonads, the brain. One known exception is the human placenta, mutations in the gene for StAR cause lipoid congenital adrenal hyperplasia, in which patients produce little steroid and can die shortly after birth. Mutations that less severely affect the function of StAR result in nonclassic lipoid CAH or familial glucocorticoid deficiency type 3, all known mutations disrupt StAR function by altering its START domain. In the case of StAR mutation, the phenotype does not present until birth since human placental steroidogenesis is independent of StAR. At the cellular level, the lack of StAR results in an accumulation of lipid within cells
Star
11.
Supergiant
–
Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute magnitudes between about −3 and −8 with temperatures spanning from about 3,500 K to over 20,000 K. The term supergiant, as applied to a star, does not have a concrete definition. The term giant star was first coined by Hertzsprung when it became apparent that the majority of stars fell into two regions of the Hertzsprung–Russell diagram. One region contained larger and more stars of spectral types A to M. Supergiant stars can be identified on the basis of their spectra, with distinctive lines sensitive to high luminosity, maury, had divided stars based on the widths of their spectral lines, with her class c identifying stars with the narrowest lines. Although it was not known at the time, these were the most luminous stars, in 1943 Morgan and Keenan formalised the definition of spectral luminosity classes, with class I referring to supergiant stars. The same system of MK luminosity classes is used today. Supergiants occur in every class from young blue class O supergiants to highly evolved red class M supergiants. Because they are enlarged compared to main-sequence and giant stars of the spectral type. Supergiants are also evolved stars with higher levels of heavy elements than main-sequence stars and this is the basis of the MK luminosity system which assigns stars to luminosity classes purely from observing their spectra. The MK system assigns stars to luminosity classes, Ib for supergiants, Ia for luminous supergiants, in reality there is very much of a continuum rather than well defined bands for these classifications, and classifications such as Iab are used for intermediate luminosity supergiants. Supergiant spectra are frequently annotated to indicate spectral peculiarities, for example B2 Iae or F5 Ipec, supergiants can also be defined as a specific phase in the evolutionary history of certain stars. Once these massive stars leave the main sequence their atmospheres inflate, stars initially under 10 M☉ will never form an iron core and in evolutionary terms do not become supergiants, although they can reach luminosities thousands of times the suns. They cannot fuse carbon and heavier elements after their core helium is exhausted, so they eventually just lose their outer layers and become a white dwarf. The phase where these stars have both hydrogen and helium burning shells is referred to as the giant branch, as stars gradually become more and more luminous class M stars. There are several categories of evolved star which are not supergiants in evolutionary terms, the dividing line becomes blurred at around 7–10 M☉ where stars start to undergo limited fusion of elements heavier than helium. Specialists studying these stars often refer to them as super AGB stars, others describe them as low-mass supergiants since they start to burn elements heavier than helium and can explode as supernovae
Supergiant
–
Direct image of the star UY Scuti, a red supergiant which is one of the largest known stars.
Supergiant
–
Hertzsprung–Russell diagram
12.
Orange giant
–
A giant star is a star with substantially larger radius and luminosity than a main-sequence star of the same surface temperature. They lie above the main sequence on the Hertzsprung–Russell diagram and correspond to luminosity classes II and III, the terms giant and dwarf were coined for stars of quite different luminosity despite similar temperature or spectral type by Ejnar Hertzsprung about 1905. Giant stars have radii up to a few hundred times the Sun, stars still more luminous than giants are referred to as supergiants and hypergiants. A hot, luminous main-sequence star may also be referred to as a giant, a star becomes a giant star after all the hydrogen available for fusion at its core has been depleted and, as a result, leaves the main sequence. The behaviour of a star depends largely on its mass. For a star with a mass above about 0.25 solar masses, the portion of the star outside the shell expands and cools, but with only a small increase in luminosity, and the star becomes a subgiant. The inert helium core continues to grow and increase temperature as it accretes helium from the shell, instead, after just a few million years the core reaches the Schönberg–Chandrasekhar limit, rapidly collapses, and may become degenerate. This causes the layers to expand even further and generates a strong convective zone that brings heavy elements to the surface in a process called the first dredge-up. The core continues to gain mass, contract, and increase in temperature, if the stars mass, when on the main sequence, was below approximately 0.4 M☉, it will never reach the central temperatures necessary to fuse helium. It will therefore remain a hydrogen-fusing red giant until it runs out of hydrogen and this is entirely theoretical because no star of such low mass has been in existence long enough to evolve to that stage. In stars above about 0.4 M☉ the core eventually reaches 108 K and helium will begin to fuse to carbon and oxygen in the core by the triple-alpha process. §5.9. When the core is degenerate helium fusion begins explosively, but most of the energy goes into lifting the degeneracy, the energy generated by helium fusion reduces the pressure in the surrounding hydrogen-burning shell, which reduces its energy-generation rate. The overall luminosity of the star decreases, its outer envelope contracts again, when the core helium is exhausted, a star with up to about 8 M☉ has a carbon–oxygen core that becomes degenerate and starts helium burning in a shell. As with the collapse of the helium core, this starts convection in the outer layers, triggers a second dredge-up. This is the giant branch analogous to the red-giant branch but more luminous. They start core-helium burning before the core becomes degenerate and develop smoothly into red supergiants without an increase in luminosity. Stars in the 8-12 M☉ range have somewhat intermediate properties and have been called super-AGB stars and they largely follow the tracks of lighter stars through RGB, HB, and AGB phases, but are massive enough to initiate core carbon burning and even some neon burning. They form oxygen–magnesium–neon cores, which may collapse in an electron-capture supernova, O class main sequence stars are already highly luminous
Orange giant
–
Internal structure of a Sun-like star and a red giant. ESO image.
Orange giant
–
Hertzsprung–Russell diagram
13.
Effective temperature
–
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is used as an estimate of a bodys surface temperature when the bodys emissivity curve is not known. When the stars or planets net emissivity in the relevant wavelength band is less than unity, the net emissivity may be low due to surface or atmospheric properties, including greenhouse effect. Notice that the luminosity of a star is then L =4 π R2 σ T e f f 4. The definition of the radius is obviously not straightforward. More rigorously the effective temperature corresponds to the temperature at the radius that is defined by a value of the Rosseland optical depth within the stellar atmosphere. The effective temperature and the bolometric luminosity are the two fundamental physical parameters needed to place a star on the Hertzsprung–Russell diagram, both effective temperature and bolometric luminosity depend on the chemical composition of a star. The effective temperature of our Sun is around 5780 kelvin, stars have a decreasing temperature gradient, going from their central core up to the atmosphere. The core temperature of the temperature at the centre of the sun where nuclear reactions take place—is estimated to be 15,000,000 K. The effective temperature of a star indicates the amount of heat that the star radiates per unit of surface area, from the warmest surfaces to the coolest is the sequence of star types known as O, B, A, F, G, K, and M. The effective temperature of a planet can be calculated by equating the power received by the planet with the emitted by a blackbody of temperature T. Take the case of a planet at a distance D from the star and we also allow the planet to reflect some of the incoming radiation by incorporating a parameter called the albedo. An albedo of 1 means that all the radiation is reflected, the effective temperature for Jupiter from this calculation is 112 K and 51 Pegasi b is 1258 K. A better estimate of effective temperature for some planets, such as Jupiter, the actual temperature depends on albedo and atmosphere effects. The actual temperature from spectroscopic analysis for HD209458 b is 1130 K, the internal heating within Jupiter raises the effective temperature to about 152 K. The surface temperature of a planet can be estimated by modifying the effective-temperature calculation to account for emissivity and this area intercepts some of the power which is spread over the surface of a sphere of radius D. We also allow the planet to some of the incoming radiation by incorporating a parameter a called the albedo. An albedo of 1 means that all the radiation is reflected, there is also a factor ε, which is the emissivity and represents atmospheric effects
Effective temperature
–
The effective temperature of the Sun (5777 K) is the temperature a black body of the same size must have to yield the same total emissive power.
14.
Urania's Mirror
–
Uranias Mirror, or, a view of the Heavens is a set of 32 astronomical star chart cards, first published in November 1824. They had illustrations based on Alexander Jamiesons A Celestial Atlas, and they were engraved by Sidney Hall, and were said to be designed by a lady, but have since been identified as the work of the Reverend Richard Rouse Bloxam, an assistant master at Rugby School. The cover of the box-set showed a depiction of Urania, the muse of astronomy, P. D. Uranias Mirror illustrates 79 constellations, some of which are now obsolete, and various subconstellations, such as Caput Medusæ. Some cards focus on a constellation, others include several, with Card 32, centered on Hydra. Card 28 has six, and no other card has more than four, each card measures 8 inches by 5 1⁄2. A book by Jehoshaphat Aspin entitled A Familiar Treatise on Astronomy was written to accompany the cards. Both the book and cards were published by Samuel Leigh,18 Strand, London, although the publishing firm had moved to 421 Strand. The cards and books came within a box illustrated with a woman almost certainly intended to be Urania, hingley calls it One of the most charming and visually attractive of the many aids to astronomical self-instruction produced in the early nineteenth century. While he had several sons, he has no other known publications. The reasons for the disguise are unknown, hingley notes that many contemporary publications attempted to suggest women had played a role in their creation, perhaps to make them sound less threatening. Ian Ridpath, noting the plagiarism of the art from A Celestial Atlas, a December 1824 advertisement, which states the cards were just published, offered the cards plain at £1/8s or fully coloured for £1/14s. This first edition did not include any stars surrounding the named constellations and this was changed for the second edition, which added back stars around theose constellations. An American edition was published in 1832, modern reprints were produced in 1993, and Barnes & Noble reproduced the American edition in 2004. The accompanying book, A Familiar Treatise on Astronomy by Jehoshaphat Aspin went through at least four editions, the second edition featured a marked expansion in content, growing from 121 pages in the first edition to 200 pages in the second. A Second Part of Uranias Mirror, which was to have included illustrations of the planets and an orrery, was advertised. Includes a video presentation of the cards
Urania's Mirror
–
Card 32 illustrates twelve constellations: nine modern ones (Corvus, Crater, Sextans, Hydra, Lupus, Centaurus, Antlia, and Pyxis), the now-subdivided Argo Navis, and the obsolete constellations Noctua, and Felis.
Urania's Mirror
–
The box lid, depicting the muse of astronomy, Urania.
Urania's Mirror
–
A Celestial Atlas, Plate 7
Urania's Mirror
–
Urania's Mirror, Plate 10
15.
Callimachus
–
Callimachus was a native of the Greek colony of Cyrene, Libya. He was a poet, critic and scholar at the Library of Alexandria and enjoyed the patronage of the Egyptian–Greek Pharaohs Ptolemy II Philadelphus. Although he was never made chief librarian, he was responsible for producing a survey based upon the contents of the Library. This, his Pinakes,120 volumes long, provided the foundation for work on the history of Greek literature. As one of the earliest critic-poets, he typifies Hellenistic scholarship, Callimachus was of Libyan Greek origin. He was named after his grandfather, an elder Callimachus, who was regarded by the Cyrenaean citizens and had served as a general. Callimachus married the daughter of a Greek man called Euphrates who came from Syracuse, however, it is unknown if they had children. In later years, he was educated in Athens, when he returned to North Africa, he moved to Alexandria. Elitist and erudite, claiming to abhor all common things, Callimachus is best known for his poems and epigrams. During the Hellenistic period, a trend in Greek-language poetry was to reject epics modelled after Homer. Big book, big evil is another saying attributed to him, often thought to be attacking long, Callimachus also wrote poems in praise of his royal patrons, and a wide variety of other poetic styles, as well as prose and criticism. Some classicists, including Peter Green, speculate that this contributed to the long feud. Though Callimachus was an opponent of big books, the Suda puts his number of works at 800, suggesting that he found large quantities of small works more acceptable. In the first three books at least, the formula appears to ask a question of the Muse, of the form, Why, on Paros, why, at Argos is a month named for lambs. Why, at Leucas, does the image of Artemis have a mortar on its head, a series of questions can be reconstituted from the fragments. One passage of the Aetia, the so-called Coma Berenices, has been reconstructed from papyrus remains, the extant hymns are extremely learned, and written in a style that some have criticised as labored and artificial. The epigrams are more widely respected, and several have been incorporated into the Greek Anthology, according to Quintilian he was the chief of the elegiac poets, his elegies were highly esteemed by the Romans, and imitated by Ovid, Catullus, and especially Sextus Propertius. Many modern classicists hold Callimachus in high regard for his influence on Latin poetry
Callimachus
–
A papyrus of Callimachus' Aetia (Pfeiffer fr. 178 = P.Oxy. XI 1362 fr. 1 col. i, 1st century AD)
16.
Homer
–
Homer is the name ascribed by the ancient Greeks to the semi-legendary author of the Iliad and the Odyssey, two epic poems which are the central works of Greek literature. The Odyssey focuses on the home of Odysseus, king of Ithaca. Many accounts of Homers life circulated in classical antiquity, the most widespread being that he was a bard from Ionia. The modern scholarly consensus is that these traditions do not have any historical value, the Homeric question - by whom, when, where and under what circumstances were the Iliad and Odyssey composed - continues to be debated. Broadly speaking, modern scholarly opinion on the authorship question falls into two camps, one group holds that most of the Iliad and the Odyssey is the work of a single poet of genius. The other considers the Homeric poems to be the crystallization of a process of working and re-working by many contributors and it is generally accepted that the poems were composed at some point around the late eighth or early seventh century B. C. Most researchers believe that the poems were transmitted orally. The Homeric epics were the greatest influence on ancient Greek culture and education, to Plato, the chronological period of Homer depends on the meaning to be assigned to the word Homer. Was Homer a single person, an imaginary person representing a group of poets and this information is often called the world of Homer. The Homeric period would in that cover a number of historical periods, especially the Mycenaean Age. Considered word-for-word, the texts as we know them are the product of the scholars of the last three centuries. Each edition of the Iliad or Odyssey is a different, as the editors rely on different manuscripts and fragments. The term accuracy reveals a belief in an original uniform text. The manuscripts of the work currently available date to no earlier than the 10th century. These are at the end of a missing thousand-year chain of copies made as each generation of manuscripts disintegrated or were lost or destroyed and these numerous manuscripts are so similar that a single original can be postulated. The time gap in the chain is bridged by the scholia, or notes, on the existing manuscripts, librarian of the Library of Alexandria, he had noticed a wide divergence in the works attributed to Homer, and was trying to restore a more authentic copy. He had collected several manuscripts, which he named, the Sinopic, the one he selected for correction was the koine, which Murray translates as the Vulgate. Aristarchus was known for his selection of material
Homer
–
Idealized portrayal of Homer dating to the Hellenistic period. British Museum.
Homer
–
Part of an 11th-century manuscript, "the Townley Homer". The writing on the top and right side are scholia.
Homer
–
Homer and His Guide, by William-Adolphe Bouguereau (1825–1905), portraying Homer on Mount Ida, beset by dogs and guided by the goatherder Glaucus (as told in Pseudo-Herodotus)
Homer
–
Raphael 's inspired Homer on Mount Parnassus.
17.
Strabo
–
Strabo was a Greek geographer, philosopher, and historian who lived in Asia Minor during the transitional period of the Roman Republic into the Roman Empire. Strabo was born to an affluent family from Amaseia in Pontus, Strabos life was characterized by extensive travels. He journeyed to Egypt and Kush, as far west as coastal Tuscany and as far south as Ethiopia in addition to his travels in Asia Minor and the time he spent in Rome. Travel throughout the Mediterranean and Near East, especially for scholarly purposes, was popular during this era and was facilitated by the relative peace enjoyed throughout the reign of Augustus. He moved to Rome in 44 BC, and stayed there, studying and writing, in 29 BC, on his way to Corinth, he visited the island of Gyaros in the Aegean Sea. Around 25 BC, he sailed up the Nile until reaching Philae and it is not known precisely when Strabos Geography was written, though comments within the work itself place the finished version within the reign of Emperor Tiberius. Some place its first drafts around 7 BC, others around 17 or 18 AD, the latest passage to which a date can be assigned is his reference to the death in AD23 of Juba II, king of Maurousia, who is said to have died just recently. He probably worked on the Geography for many years and revised it steadily, on the presumption that recently means within a year, Strabo stopped writing that year or the next, when he died. The first of Strabos major works, Historical Sketches, written while he was in Rome, is completely lost. Strabo studied under several prominent teachers of various specialties throughout his life at different stops along his Mediterranean travels. His first chapter of education took place in Nysa under the master of rhetoric Aristodemus, Strabo was an admirer of Homers poetry, perhaps a consequence of his time spent in Nysa with Aristodemus. At around the age of 21, Strabo moved to Rome, where he studied philosophy with the Peripatetic Xenarchus, despite Xenarchuss Aristotelian leanings, Strabo later gives evidence to have formed his own Stoic inclinations. In Rome, he learned grammar under the rich and famous scholar Tyrannion of Amisus. Although Tyrannion was also a Peripatetic, he was more relevantly a respected authority on geography, the final noteworthy mentor to Strabo was Athenodorus Cananites, a philosopher who had spent his life since 44 BC in Rome forging relationships with the Roman elite. Athenodorus endowed to Strabo three important items, his philosophy, his knowledge, and his contacts, moreover, from his own first-hand experience, Athenodorus provided Strabo with information about regions of the empire which he would not otherwise have known. Strabo is most notable for his work Geographica, which presented a history of people. Although the Geographica was rarely utilized in its antiquity, a multitude of copies survived throughout the Byzantine Empire. It first appeared in Western Europe in Rome as a Latin translation issued around 1469, the first Greek edition was published in 1516 in Venice
Strabo
–
Strabo as depicted in a 16th-century engraving
Strabo
–
Title page from Isaac Casaubon 's 1620 edition of Geographica.
Strabo
–
Statue of Strabo in his hometown (modern-day Amasya, Turkey), beside the Iris (Yeşilırmak) River.
Strabo
–
Map of Europe according to Strabo.
18.
Thales
–
Thales of Miletus was a pre-Socratic Greek/Phoenician philosopher, mathematician and astronomer from Miletus in Asia Minor. He was one of the Seven Sages of Greece, Thales is recognized for breaking from the use of mythology to explain the world and the universe, and instead explaining natural objects and phenomena by theories and hypothesis, i. e. science. Aristotle reported Thales hypothesis that the principle of nature and the nature of matter was a single material substance. In mathematics, Thales used geometry to calculate the heights of pyramids and he is the first known individual to use deductive reasoning applied to geometry, by deriving four corollaries to Thales theorem. He is the first known individual to whom a mathematical discovery has been attributed, the ancient source, Apollodorus of Athens, writing during the 2nd century BCE, thought Thales was born about the year 625 BCE. The dates of Thales life are not exactly known, but are roughly established by a few events mentioned in the sources. According to Herodotus Thales predicted the eclipse of May 28,585 BC. Diogenes Laërtius quotes the chronicle of Apollodorus of Athens as saying that Thales died at the age of 78 during the 58th Olympiad and attributes his death to heat stroke while watching the games. Plutarch had earlier told this version, Solon visited Thales and asked him why he remained single, nevertheless, several years later, anxious for family, he adopted his nephew Cybisthus. Thales involved himself in many activities, taking the role of an innovator, some say that he left no writings, others say that he wrote On the Solstice and On the Equinox. Diogenes Laërtius quotes two letters from Thales, one to Pherecydes of Syros, offering to review his book on religion, Thales identifies the Milesians as Athenian colonists. He was aware of the existence of the lodestone, and was the first to be connected to knowledge of this in history, according to Aristotle, Thales thought lodestones had souls, because iron is attracted to them. According to Hieronymus, historically quoted by Diogenes Laertius, Thales found the height of pyramids by comparison between the lengths of the shadows cast by a person and by the pyramids, several anecdotes suggest Thales was not just a philosopher, but also a businessman. A story, with different versions, recounts how Thales achieved riches from an olive harvest by prediction of the weather, in one version, he bought all the olive presses in Miletus after predicting the weather and a good harvest for a particular year. Thales’ political life had mainly to do with the involvement of the Ionians in the defense of Anatolia against the power of the Persians. In neighbouring Lydia, a king had come to power, Croesus and he had conquered most of the states of coastal Anatolia, including the cities of the Ionians. The story is told in Herodotus, the war endured for five years, but in the sixth an eclipse of the Sun spontaneously halted a battle in progress. It seems that Thales had predicted this solar eclipse, the Seven Sages were most likely already in existence, as Croesus was also heavily influenced by Solon of Athens, another sage
Thales
–
Thales of Miletus
Thales
–
An olive mill and an olive press dating from Roman times in Capernaum, Israel.
Thales
–
Total eclipse of the Sun
Thales
–
The Ionic Stoa on the Sacred Way in Miletus
19.
Classical antiquity
–
It is the period in which Greek and Roman society flourished and wielded great influence throughout Europe, North Africa and Southwestern Asia. Conventionally, it is taken to begin with the earliest-recorded Epic Greek poetry of Homer, and continues through the emergence of Christianity and it ends with the dissolution of classical culture at the close of Late Antiquity, blending into the Early Middle Ages. Such a wide sampling of history and territory covers many disparate cultures, Classical antiquity may refer also to an idealised vision among later people of what was, in Edgar Allan Poes words, the glory that was Greece, and the grandeur that was Rome. The culture of the ancient Greeks, together with influences from the ancient Near East, was the basis of art, philosophy, society. The earliest period of classical antiquity takes place before the background of gradual re-appearance of historical sources following the Bronze Age collapse, the 8th and 7th centuries BC are still largely proto-historical, with the earliest Greek alphabetic inscriptions appearing in the first half of the 8th century. Homer is usually assumed to have lived in the 8th or 7th century BC, in the same period falls the traditional date for the establishment of the Ancient Olympic Games, in 776 BC. The Phoenicians originally expanded from Canaan ports, by the 8th century dominating trade in the Mediterranean, carthage was founded in 814 BC, and the Carthaginians by 700 BC had firmly established strongholds in Sicily, Italy and Sardinia, which created conflicts of interest with Etruria. The Etruscans had established control in the region by the late 7th century BC, forming the aristocratic. According to legend, Rome was founded on April 21,753 BC by twin descendants of the Trojan prince Aeneas, Romulus and Remus. As the city was bereft of women, legend says that the Latins invited the Sabines to a festival and stole their unmarried maidens, leading to the integration of the Latins and the Sabines. Archaeological evidence indeed shows first traces of settlement at the Roman Forum in the mid-8th century BC, the seventh and final king of Rome was Tarquinius Superbus. As the son of Tarquinius Priscus and the son-in-law of Servius Tullius, Superbus was of Etruscan birth and it was during his reign that the Etruscans reached their apex of power. Superbus removed and destroyed all the Sabine shrines and altars from the Tarpeian Rock, the people came to object to his rule when he failed to recognize the rape of Lucretia, a patrician Roman, at the hands of his own son. Lucretias kinsman, Lucius Junius Brutus, summoned the Senate and had Superbus, after Superbus expulsion, the Senate voted to never again allow the rule of a king and reformed Rome into a republican government in 509 BC. In fact the Latin word Rex meaning King became a dirty and hated throughout the Republic. In 510, Spartan troops helped the Athenians overthrow the tyrant Hippias, cleomenes I, king of Sparta, put in place a pro-Spartan oligarchy conducted by Isagoras. Greece entered the 4th century under Spartan hegemony, but by 395 BC the Spartan rulers removed Lysander from office, and Sparta lost her naval supremacy. Athens, Argos, Thebes and Corinth, the two of which were formerly Spartan allies, challenged Spartan dominance in the Corinthian War, which ended inconclusively in 387 BC
Classical antiquity
–
The Parthenon is one of the most iconic symbols of the classical era, exemplifying ancient Greek culture
20.
Alpha Ursae Minoris
–
Polaris, designated Alpha Ursae Minoris, commonly the North Star or Pole Star, is the brightest star in the constellation of Ursa Minor. It is very close to the celestial pole, making it the current northern pole star. The revised Hipparcos parallax gives a distance to Polaris of about 433 light-years, Polaris is a multiple star, comprising the main star in orbit with a smaller companion, the pair in orbit with Polaris B. There were once thought to be two more distant components—Polaris C and Polaris D—but these have been not to be physically associated with the Polaris system. Polaris Aa is a 4.5 solar mass F7 yellow supergiant of spectral type Ib and this is the first classical Cepheid to have a mass determined from its orbit. William Herschel discovered the star in 1780 while using a hand-built reflecting telescope, in 1929 it was discovered, by examining the spectrum of Polaris A, that it was a very close binary, with the secondary being a dwarf, which had been theorized in earlier observations. In January 2006, NASA released images, from the Hubble telescope, that showed the three members of the Polaris ternary system. The nearest dwarf star is in an orbit of only 18.5 au from Polaris A, about the distance between the Sun and Uranus), which explains why its light is swamped by its close and much brighter companion. Polaris A, the supergiant primary component, is a low-amplitude Population I classical Cepheid variable, cepheids constitute an important standard candle for determining distance, so Polaris, as the closest such star, is heavily studied. The variability of Polaris had been suspected since 1852, this variation was confirmed by Ejnar Hertzsprung in 1911, the range of brightness of Polaris during its pulsations is given as 1. 86–2.13, but the amplitude has changed since discovery. Prior to 1963, the amplitude was over 0.1 magnitude and was gradually decreasing. After 1966 it very rapidly decreased until it was less than 0.05 magnitude, since then and it has been reported that the amplitude is now increasing again, a reversal not seen in any other Cepheid. The period, roughly 4 days, has changed over time. It has steadily increased by around 4.5 seconds per year except for a hiatus in 1963–1965 and this was originally thought to be due to secular redward evolution across the Cepheid instability strip, but it may be due to interference between the primary and the first-overtone pulsation modes. Authors disagree on whether Polaris is a fundamental or first-overtone pulsator, the temperature of Polaris varies by only a small amount during its pulsations, but the amount of this variation is variable and unpredictable. The erratic changes of temperature and the amplitude of changes during each cycle, from less than 50 K to at least 170 K. Research reported in Science suggests that Polaris is 2.5 times brighter today than when Ptolemy observed it, because of its importance in celestial navigation, Polaris is known by numerous names. It became known as Polaris during the Renaissance, its derived from the Latin polaris of/near the pole
Alpha Ursae Minoris
–
Polaris as seen by the Hubble Space Telescope.
Alpha Ursae Minoris
–
This artist's concept shows three class F stars: supergiant Polaris A, dwarf Polaris Ab, and its distant dwarf companion, Polaris B
Alpha Ursae Minoris
–
A typical Northern Hemisphere star trail with Polaris in the center
Alpha Ursae Minoris
–
Ursa Major and Ursa Minor in relation to Polaris
21.
New Latin
–
New Latin was a revival in the use of Latin in original, scholarly, and scientific works between c.1375 and c. Modern scholarly and technical nomenclature, such as in zoological and botanical taxonomy and international scientific vocabulary, in such use, New Latin is often viewed as still existing and subject to new word formation. As a language for full expression in prose or poetry, however, classicists use the term Neo-Latin to describe the Latin that developed in Renaissance Italy as a result of renewed interest in classical civilization in the 14th and 15th centuries. Neo-Latin also describes the use of the Latin language for any purpose, scientific or literary, during, the term New Latin came into widespread use towards the end of the 1890s among linguists and scientists. New Latin was, at least in its days, an international language used throughout Catholic and Protestant Europe. Russias acquisition of Kiev in the later 17th century introduced the study of Latin to Russia, though Latin and New Latin are considered extinct, large parts of their vocabulary have seeped into English and several Germanic languages. New Latin was inaugurated by the triumph of the humanist reform of Latin education, led by writers as Erasmus, More. Medieval Latin had been the working language of the Roman Catholic Church, taught throughout Europe to aspiring clerics. It was a language, full of neologisms and often composed without reference to the grammar or style of classical authors. Attempts at reforming Latin use occurred sporadically throughout the period, becoming most successful in the mid-to-late 19th century, the Protestant Reformation, though it removed Latin from the liturgies of the churches of Northern Europe, may have advanced the cause of the new secular Latin. Classic works such as Newtons Principia Mathematica were written in the language, throughout this period, Latin was a universal school subject, and indeed, the pre-eminent subject for elementary education in most of Europe and other places of the world that shared its culture. All universities required Latin proficiency to obtain admittance as a student, Latin was an official language of Poland—recognised and widely used between the 9th and 18th centuries, commonly used in foreign relations and popular as a second language among some of the nobility. As an auxiliary language to the local vernaculars, New Latin appeared in a variety of documents, ecclesiastical, legal, diplomatic, academic. As late as the 1720s, Latin was still used conversationally, for instance, the Hanoverian king George I of Great Britain, who had no command of spoken English, communicated in Latin with his Prime Minister Robert Walpole, who knew neither German nor French. By about 1700, the movement for the use of national languages had reached academia, and an example of the transition is Newtons writing career. A much earlier example is Galileo c,1600, some of whose scientific writings were in Latin, some in Italian, the latter to reach a wider audience. Likewise, in the early 18th century, French replaced Latin as a diplomatic language, at the same time, some were dismissing Latin as a useless accomplishment, unfit for a man of practical affairs. The last international treaty to be written in Latin was the Treaty of Vienna in 1738, a diminishing audience combined with diminishing production of Latin texts pushed Latin into a declining spiral from which it has not recovered
New Latin
–
Linnaeus, 10th edition of Systema Naturae is a famous New Latin text.
New Latin
–
This pocket watch made for the medical community has Latin instructions for measuring a patient's pulse rate on its dial: enumeras ad XX pulsus, "you count to 20 beats".
New Latin
–
Handwriting in Latin from 1595
New Latin
–
Erasmus by Holbein
22.
Nymph
–
A nymph in Greek mythology and in Latin mythology is a minor female nature deity typically associated with a particular location or landform. They are beloved by many and dwell in mountainous regions and forests by lakes, charybdis and Scylla were once nymphs. Other nymphs, always in the shape of young maidens, were part of the retinue of a god, such as Dionysus, Hermes, or Pan, or a goddess, nymphs were the frequent target of satyrs. The Greek word νύμφη has bride and veiled among its meanings, other readers refer the word to a root expressing the idea of swelling. The mythologies of classicizing Roman poets were unlikely to have affected the rites and cult of individual nymphs venerated by people in the springs. Among the Roman literate class, their sphere of influence was restricted, the ancient Greek belief in nymphs survived in many parts of the country into the early years of the twentieth century, when they were usually known as nereids. At that time, John Cuthbert Lawson wrote and they might appear in a whirlwind. Such encounters could be dangerous, bringing dumbness, besotted infatuation, when parents believed their child to be nereid-struck, they would pray to Saint Artemidos. Due to widespread use of the term among lay persons and stereotypes attached, professionals nowadays prefer the term hypersexuality, the word nymphet is used to identify a sexually precocious girl. The term was made famous in the novel Lolita by Vladimir Nabokov, the main character, Humbert Humbert, uses the term many times, usually in reference to the title character. Thus the classes of nymphs tend to overlap, which complicates the task of precise classification, rose mentions dryads and hamadryads as nymphs of trees generally, meliai as nymphs of ash trees, and naiads as nymphs of water, but no others specifically. She is the consort of Acheron, and the mother of Ascalaphus, leuce, lover of Hades Minthe, lover of Hades, rival of Persephone Melinoe Orphic nymph, daughter of Persephone and Zeus disguised as Pluto. Her name is an epithet of Hecate. Nymphs in such groupings could belong to any of the mentioned above. For lists of Naiads, Oceanids, Dryades etc and this motif supposedly came from an Italian report of a Roman sculpture of a nymph at a fountain above the River Danube
Nymph
–
In this 1896 painting by John William Waterhouse, Hylas is abducted by the Naiads, i.e. fresh water nymphs
Nymph
–
Nymph with morning glory flowers
Nymph
–
Nymphe by Gaston Bussière
Nymph
–
Cave of the Storm Nymphs by Sir Edward John Poynter
23.
Lycosura
–
Lycosura was a city of Arcadia said by Pausanias to be the oldest city in the world, though there is no evidence for its existence before the fourth century BCE. The dates of both the temple and the group have occasioned some dispute. Remains of a stoa, altars and other structures have also been found, the Sanctuary of Despoina at Lycosoura is located 9 km WSW of Megalopolis,6.9 km SSE of Mount Lykaion, and 160 km SW of Athens. Her real name could not be revealed to anyone except those initiated to her mysteries at Lycosura and he relates that Lycosura was founded by Lycaon the son of Pelasgus, and that it was the oldest city in the world. He notes that Cleitor, the grandson of Arcas, dwelled in Lycosura, in 368/7 BCE, when many cities in the region were unified into the city of Megalopolis through persuasion or force, the citizens of Lycosura, Trapezus, Lycaea, and Tricoloni refused to relocate. The citizens of Trapezus were massacred or driven into exile by the Arcadians, but the citizens of Lycosura were spared due to reverence for the Sanctuary of Despoina, many of the cities of the region were thus abandoned in favor of Megalopolis and their sanctuaries fell out of use. Pausanias states that the Sanctuary of Despoina was 40 stades from Megalopolis, in the 2nd century CE a statue of the emperor Hadrian was dedicated in the temple. Coins from Megalopolis of the Severan period in the early 3rd century appear to depict the cult statue group, despite its significance to the Arcadians and occasional notice from the wider Mediterranean world, the cult of Despoina appears to have remained tied to this one sanctuary at Lycosura. The site of Lycosura occupies a hill of 632 m in the wooded, the Sanctuary of Despoina is sited in a declivity on the north-eastern face of the hill occupied by the city. The temple and considerable remains of the statuary group were discovered in 1889 CE by the Greek Archaeological Society. Dating of the finds and structures thus remains problematic, although later excavations, traces of the temenos wall have been detected on the north and the east sides of the sanctuary, the southern and western limits of the sacred area are thus unknown. The Temple of Despoina is prostyle-hexastyle in plan and in the Doric order - i. e. it had six Doric columns across the front façade only. In plan, the stylobate of the temple measures 11.15 by 21.35 m and is divided between a pronaos and a cella, the six columns of the façade are in marble, as is the entablature. A curious feature of temple is the doorway in the south wall facing the theater-like area. Although uncommon, side doorways are known from other temples in Arkadia, i. e. Athena Alea at Tegea, and Apollo Epikourios at Bassai. Rather than extending as steps along the four sides of the temple, the architecture also deviates from the standard Doric schema in that its Doric frieze is 1. 5x the height of the architrave. At the rear of the cella is a massive, c, 1m high stone podium designed to hold the cult statuary group, in front of which is a mosaic decorating the floor. General consensus holds that the first construction of this dates to the 4th century BCE
Lycosura
–
View SE toward the Temple of Despoina at Lycosoura.
Lycosura
–
Area shaded purple approximates the sacred precinct.
24.
Akkadian language
–
Akkadian is an extinct East Semitic language that was spoken in ancient Mesopotamia. The earliest attested Semitic language, it used the writing system, which was originally used to write the unrelated Ancient Sumerian. The language was named after the city of Akkad, a centre of Mesopotamian civilization during the Akkadian Empire. The mutual influence between Sumerian and Akkadian had led scholars to describe the languages as a sprachbund, Akkadian proper names were first attested in Sumerian texts from around the mid 3rd-millennium BC. From the second half of the third millennium BC, texts written in Akkadian begin to appear. By the second millennium BC, two variant forms of the language were in use in Assyria and Babylonia, known as Assyrian and Babylonian respectively, for centuries, Akkadian was the native language in Mesopotamian nations such as Assyria and Babylonia. However, it began to decline during the Neo-Assyrian Empire around the 8th century BC, by the Hellenistic period, the language was largely confined to scholars and priests working in temples in Assyria and Babylonia. The last known Akkadian cuneiform document dates from the 1st century AD, Akkadian belongs with the other Semitic languages in the Near Eastern branch of the Afroasiatic languages, a family native to East Africa, which then spread to West, Northwest and Northeast Africa. Within the Near Eastern Semitic languages, Akkadian forms an East Semitic subgroup and this novel word order is due to the influence of the Sumerian substratum, which has an SOV order. Additionally Akkadian is the only Semitic language to use the prepositions ina and ana, other Semitic languages like Arabic and Aramaic have the prepositions bi/bə and li/lə. The origin of the Akkadian spatial prepositions is unknown, in contrast to most other Semitic languages, Akkadian has only one non-sibilant fricative, ḫ. Akkadian lost both the glottal and pharyngeal fricatives, which are characteristic of the other Semitic languages, until the Old Babylonian period, the Akkadian sibilants were exclusively affricated. Old Akkadian is preserved on clay tablets dating back to c.2500 BC and it was written using cuneiform, a script adopted from the Sumerians using wedge-shaped symbols pressed in wet clay. As employed by Akkadian scribes, the cuneiform script could represent either Sumerian logograms, Sumerian syllables, Akkadian syllables. For this reason, the sign AN can on the one hand be a logogram for the word ilum, additionally, this sign was used as a determinative for divine names. Another peculiarity of Akkadian cuneiform is that many signs do not have a phonetic value. Certain signs, such as AḪ, do not distinguish between the different vowel qualities, nor is there any coordination in the other direction, the syllable -ša-, for example, is rendered by the sign ŠA, but also by the sign NĪĜ. Both of these are used for the same syllable in the same text
Akkadian language
–
An Akkadian inscription
Akkadian language
–
Cuneiform writing (Neoassyrian script) (1 = Logogram (LG) "mix"/syllabogram (SG) ḫi, 2 = LG "moat", 3 = SG aʾ, 4 = SG aḫ, eḫ, iḫ, uḫ, 5 = SG kam, 6 = SG im, 7 = SG bir)
Akkadian language
–
The Deluge tablet of the Gilgamesh epic in Akkadian.
Akkadian language
–
Geography
25.
Oxen
–
An ox, also known as a bullock in Australia and India, is a bovine trained as a draft animal. Oxen are commonly castrated adult male cattle, castration makes the animals easier to control, cows or bulls may also be used in some areas. Oxen are used for plowing, for transport, for threshing grain by trampling, oxen may be also used to skid logs in forests, particularly in low-impact, select-cut logging. Oxen are usually yoked in pairs, light work such as carting household items on good roads might require just one pair, while for heavier work, further pairs would be added as necessary. A team used for a load over difficult ground might exceed nine or ten pairs. Oxen are thought to have first been harnessed and put to work around 4000 BC, working oxen are taught to respond to the signals of the teamster, bullocky or ox-driver. These signals are given by verbal command and body language, reinforced by a goad, in pre-industrial times, most teamsters were known for their loud voices and forthright language. Verbal commands for draft animals vary widely throughout the world and their teamster makes or buys as many as a dozen yokes of different sizes for each animal as it grows. The steers are normally considered fully trained at the age of four, a tradition in south eastern England was to use oxen as dual-purpose animals, for draft and beef. A plowing team of eight oxen normally consisted of four pairs aged a year apart, each year, a pair of steers of about three years of age would be bought for the team and trained with the older animals. The pair would be kept for four years, then sold at about seven years old to be fattened for beef – thus covering much of the cost of buying that years new pair. Use of oxen for plowing survived in areas of England until the early twentieth century. Pairs of oxen were always hitched the same way round, in southern England it was traditional to call the near-side ox of a pair by a single-syllable name and the off-side one by a longer one. Ox trainers favour larger animals for their ability to do more work, oxen are therefore usually of larger breeds, and are usually males because they are generally larger. Females can also be trained as oxen, but as well as being smaller, are more valued for producing calves. Bulls are also used in parts of the world, especially Asia. Working oxen usually require shoes, although in England not all working oxen were shod, since their hooves are cloven, two shoes or ox cues are required for each hoof, unlike the single shoe of a horse. Ox shoes are usually of approximately half-moon or banana shape, either with or without caulkins, unlike horses, oxen are not easily able to balance on three legs while a farrier shoes the fourth
Oxen
–
Zebu oxen in Mumbai, India.
Oxen
–
Oxen used in farms for plowing.
Oxen
–
A team of ten pairs of oxen in Australia.
Oxen
–
A single left-hand ox shoe of the type used for large Chianina oxen in Tuscany
26.
Chinese astronomy
–
Astronomy in China has a very long history, with historians indicating that the Chinese were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs. Detailed records of observations began during the Warring States period. The telescope was introduced in the seventeenth century, in 1669, the Peking observatory was completely redesigned and refitted under the direction of Ferdinand Verbiest. Today, China continues to be active in astronomy, with many observatories, one of the main functions was for the purpose of timekeeping. The Chinese used a calendar, but, because the cycles of the sun. The Chinese calendar was considered to be a symbol of a dynasty, as dynasties would rise and fall, astronomers and astrologers of each period would often prepare a new calendar to be made, with observations for that purpose. Astrological divination was also an important part of astronomy, astronomers took careful note of guest stars, which suddenly appeared among the fixed stars. Ancient astronomical records of phenomena like comets and supernovae are used in modern astronomical studies. The Chinese developed three different cosmological models, the Gai Tian, or hemispherical dome, model conceived the heavens as a hemisphere lying over a dome-shaped earth. The second cosmological model, associated with the Hun Tian school, saw the heavens as a celestial sphere not unlike the spherical models developed in the Greek, the divisions of the sky began with the Northern Dipper and the 28 mansions. In 1977, a box was excavated from the tomb of Yi. Names of the 28 lunar mansions were found on the cover of the box, as lunar mansions have such an ancient origin, the meanings of most of their names have become obscure. Even worse, the name of each lunar mansion consists of only one Chinese word, the meanings of the names are still under discussion. Besides the 28 lunar mansions, most constellations are based on the works of Shi Shen-fu and Gan De, in the fourth century BC, the two Chinese astronomers responsible for the earliest information going into the star catalogues were Shi Shen and Gan De of the Warring States period. These books appeared to have lasted until the sixth century, but were lost after that, a number of books share similar names, often quoted and named after them. These texts should not be confused with the original written by them. Notable works that helped preserve the contents include, Wu Xian has been one of the astronomers in debate and he is often represented as one of the Three Schools Astronomical tradition along with Gan and Shi. Moreover, it was customary in the past for the Chinese to forge works of notable scholars, Wu Xian is generally mentioned as the astronomer who lived many years before Gan and Shi
Chinese astronomy
–
The Dunhuang map from the Tang Dynasty (North Polar region). This map is thought to date from the reign of Emperor Zhongzong of Tang (705–710). Founded in Dunhuang, Gansu. Constellations of the three schools were distinguished with different colors: white, black and yellow for stars of Wu Xian, Gan De and Shi Shen respectively. The whole set of star maps contained 1,300 stars.
Chinese astronomy
–
Wide view of the Crab Nebula.
Chinese astronomy
–
A star map with a cylindrical projection. Su Song's star maps represent the oldest existent ones in printed form.
Chinese astronomy
–
A method of making observation instruments at the times of Qing Dynasty
27.
Alpha Ursae Majoris
–
Alpha Ursae Majoris, also named Dubhe, is the second-brightest star in the constellation of Ursa Major. Alpha Ursae Majoris forms part of the Big Dipper, and is the northern of the pointers, Dubhe is about 123 light years from the Sun and is a giant star that has evolved away from the main sequence after consuming the hydrogen at its core. It is a binary with a main sequence companion α UMa B that has a stellar classification of F0V. The companion star orbits at a separation of about 23 astronomical units. There is another spectroscopic binary 8 arc minutes distant, a 7th magnitude pair showing an F8 spectral type and it is sometimes referred to as Alpha Ursae majoris C, but is separately catalogued as HD95638. α Ursae Majoris has been reported to vary in brightness by about a thousandth of a magnitude, ten radial oscillation modes have been detected, with periods between 6.4 hours and 6.4 days. Although it is part of the constellation of Ursa Major, it does not form part of the Ursa Major Moving Group of stars that have a motion through space. α Ursae Majoris is the stars Bayer designation and it bore the traditional names Dubhe and Ak. Dubhe derives from the Arabic for bear, dubb, from the phrase ظهر الدب الاكبر żahr ad-dubb al-akbar the back of the Greater Bear, the rarer Ak means The Eye. In 2016, the International Astronomical Union organized a Working Group on Star Names to catalog, the WGSNs first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Dubhe for this star. The Hindus refer to the star as Kratu, one of the Seven Rishis, consequently, Alpha Ursae Majoris itself is known as 北斗一 Běi Dǒu yī, and 天樞 Tiān Shū. Dubhe is the star of the State of Utah. Dubhe was a ship in the United States Navy, the Danish National Home Guard Navy ship MHV806 is also named Dubhe
Alpha Ursae Majoris
–
Dubhe "A" and faint companion binaries
Alpha Ursae Majoris
28.
Beta Ursae Majoris
–
Beta Ursae Majoris, also named Merak, is a star in the northern circumpolar constellation of Ursa Major. The apparent visual magnitude of this star is +2.37, extending an imaginary straight line from this star through the nearby Alpha Ursae Majoris extends to Polaris, the north star. Based upon parallax measurements of star, it is located at a distance of 79.7 light-years from the Sun. The spectrum shows this to have a classification of A1 V. The effective temperature of the envelope is about 9,225 K. It is larger than the Sun, with about 2.7 times the mass and 2.84 times the Solar radius. If they were viewed from the distance, Beta Ursae Majoris would appear much brighter than the Sun. The dust has a mass of about 0. 27% the mass of the Earth. This group has an age of about million years. As the members of this group share an origin and motion through space. β Ursae Majoris is the stars Bayer designation and it bore the traditional name Merak derived from the Arabic المراق al-maraqq the loins. In 2016, the International Astronomical Union organized a Working Group on Star Names to catalog, the WGSNs first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Merak for this star. The Hindus called the star Pulaha, one of the Seven Rishis, consequently, Beta Ursae Majoris itself is known as 北斗二 and 天璇. USS Merak and USS Merak, both of United States navy ship, in the original Star Trek series episode The Cloud Minders, the planet Merak II is said to be suffering from a botanical plague that can only be treated by the use of the mineral zenite. The video game Devil Survivor 2 features Merak, alongside the other stars of the Big Digger, as the Septentrione, Merak features on the 2nd day in Osaka, Japan. In the anime Saint Seiya, also known as Knights of the Zodiac, hagen is the name of the God Warrior representing the star Beta Merak
Beta Ursae Majoris
29.
Equatorial coordinate system
–
The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects. The origin at the center of the Earth means the coordinates are geocentric, a right-handed convention means that coordinates are positive toward the north and toward the east in the fundamental plane. This description of the orientation of the frame is somewhat simplified. A slow motion of Earths axis, precession, causes a slow, continuous turning of the system westward about the poles of the ecliptic. Superimposed on this is a motion of the ecliptic. In order to fix the primary direction, these motions necessitate the specification of the equinox of a particular date, known as an epoch. The three most commonly used are, Mean equinox of an epoch is a fixed standard direction. Mean equinox of date is the intersection of the ecliptic of date with the mean equator, commonly used in planetary orbit calculation. True equinox of date is the intersection of the ecliptic of date with the true equator and this is the actual intersection of the two planes at any particular moment, with all motions accounted for. A position in the coordinate system is thus typically specified true equinox and equator of date, mean equinox and equator of J2000.0. Note that there is no mean ecliptic, as the ecliptic is not subject to small periodic oscillations, a stars spherical coordinates are often expressed as a pair, right ascension and declination, without a distance coordinate. The direction of distant objects is the same for all observers. Telescopes equipped with equatorial mounts and setting circles employ the equatorial coordinate system to find objects, setting circles in conjunction with a star chart or ephemeris allow the telescope to be easily pointed at known objects on the celestial sphere. The declination symbol δ, measures the distance of an object perpendicular to the celestial equator, positive to the north. For example, the celestial pole has a declination of +90°. The origin for declination is the equator, which is the projection of the Earths equator onto the celestial sphere. Declination is analogous to terrestrial latitude, the right ascension symbol α, measures the angular distance of an object eastward along the celestial equator from the vernal equinox to the hour circle passing through the object. The vernal equinox point is one of the two where the ecliptic intersects the celestial equator, there are = 15° in one hour of right ascension, 24h of right ascension around the entire celestial equator
Equatorial coordinate system
–
As seen from above the Earth 's north pole, a star's local hour angle (LHA) for an observer near New York (red). Also depicted are the star's right ascension and Greenwich hour angle (GHA), the local mean sidereal time (LMST) and Greenwich mean sidereal time (GMST). The symbol ʏ identifies the vernal equinox direction.
30.
Johann Bayer
–
Johann Bayer was a German lawyer and uranographer. He was born in Rain, Lower Bavaria, in 1572, Bayer had several interests outside his work, including archaeology and mathematics. However, he is known for his work in astronomy. He remained unmarried and died in 1625, Bayer is most famous for his star atlas Uranometria Omnium Asterismorum, which was first published in 1603 in Augsburg and dedicated to two prominent local citizens. This was the first atlas to cover the entire celestial sphere and it was based upon the work of Tycho Brahe and may have borrowed from Alessandro Piccolominis 1540 star atlas, De le stelle fisse, although Bayer included an additional 1,000 stars. The Uranometria introduced a new system of star designation which has known as the Bayer designation. Bayers atlas included twelve new constellations invented a few years earlier to fill in the far south of the night sky, the crater Bayer on the Moon is named after him. Julius Schiller Bayer designation Full digital facsimile, Linda Hall Library
Johann Bayer
–
The constellation Orion in Bayer's Uranometria
31.
Alpha
–
Alpha is the first letter of the Greek alphabet. In the system of Greek numerals it has a value of 1 and it was derived from the Phoenician and Hebrew letter aleph - an ox or leader. Letters that arose from alpha include the Latin A and the Cyrillic letter А, in English, the noun alpha is used as a synonym for beginning, or first, reflecting its Greek roots. In Ancient Greek, alpha was pronounced and could be either long or short. Where there is ambiguity, long and short alpha are sometimes written with a macron and breve today, Ᾱᾱ, ὥρα = ὥρᾱ hōrā a time γλῶσσα = γλῶσσᾰ glôssa tongue In Modern Greek, vowel length has been lost, and all instances of alpha simply represent. It can also combine with the iota subscript, in the Attic-Ionic dialect of Ancient Greek, long alpha fronted to. In Ionic, the took place in all positions. In Attic, the shift did not take place after epsilon, iota, in Doric and Aeolic, long alpha is preserved in all positions. It originates from the Proto-Indo-European *n̥- and is cognate with English un-, copulative a is the Greek prefix ἁ- or ἀ- ha-, a-. The letter alpha represents various concepts in physics and chemistry, including radiation, angular acceleration, alpha particles, alpha carbon. Alpha also stands for thermal expansion coefficient of a compound in physical chemistry and it is also commonly used in mathematics in algebraic solutions representing quantities such as angles. Furthermore, in mathematics, the alpha is used to denote the area underneath a normal curve in statistics to denote significance level when proving null. In zoology, it is used to name the dominant individual in a wolf or dog pack, the proportionality operator ∝ is sometimes mistaken for alpha. The uppercase letter alpha is not generally used as a symbol because it tends to be rendered identically to the uppercase Latin A, in the International Phonetic Alphabet, a letter based on the lower case of alpha represents the open back unrounded vowel. Alpha was derived from aleph, which in Phoenician means ox, plutarch, in Moralia, presents a discussion on why the letter alpha stands first in the alphabet. He then added that he would rather be assisted by Lamprias, his own grandfather, than by Dionysus grandfather, according to Plutarchs natural order of attribution of the vowels to the planets, alpha was connected with the Moon. Alpha, both as a symbol and term, is used to refer to or describe a variety of things, the New Testament has God declaring himself to be the Alpha and Omega, the beginning and the end, the first and the last. The term alpha has been used to position in social hierarchy
Alpha
–
Memorial Stained Glass window, Royal Military College of Canada features Alpha and Omega
32.
Spectral type
–
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with absorption lines, each line indicates an ion of a certain chemical element, with the line strength indicating the abundance of that ion. The relative abundance of the different ions varies with the temperature of the photosphere, the spectral class of a star is a short code summarizing the ionization state, giving an objective measure of the photospheres temperature and density. Most stars are classified under the Morgan–Keenan system using the letters O, B, A, F, G, K, and M. Each letter class is subdivided using a numeric digit with 0 being hottest and 9 being coolest. The sequence has been expanded with classes for other stars and star-like objects that do not fit in the system, such as class D for white dwarfs. In the MK system, a luminosity class is added to the class using Roman numerals. This is based on the width of absorption lines in the stars spectrum. The full spectral class for the Sun is then G2V, indicating a main-sequence star with a temperature around 5,800 K, the conventional color description takes into account only the peak of the stellar spectrum. This means that the assignment of colors of the spectrum can be misleading. There are no green, indigo, or violet stars, likewise, the brown dwarfs do not literally appear brown. The modern classification system is known as the Morgan–Keenan classification, each star is assigned a spectral class from the older Harvard spectral classification and a luminosity class using Roman numerals as explained below, forming the stars spectral type. The spectral classes O through M, as well as more specialized classes discussed later, are subdivided by Arabic numerals. For example, A0 denotes the hottest stars in the A class, fractional numbers are allowed, for example, the star Mu Normae is classified as O9.7. The Sun is classified as G2, the conventional color descriptions are traditional in astronomy, and represent colors relative to the mean color of an A-class star, which is considered to be white. The apparent color descriptions are what the observer would see if trying to describe the stars under a dark sky without aid to the eye, or with binoculars. However, most stars in the sky, except the brightest ones, red supergiants are cooler and redder than dwarfs of the same spectral type, and stars with particular spectral features such as carbon stars may be far redder than any black body. O-, B-, and A-type stars are called early type
Spectral type
–
Secchi spectral types (152 Schjellerup is Y Canum Venaticorum)
Spectral type
–
Hertzsprung–Russell diagram
Spectral type
–
Artist's impression of Aludra, a B5 supergiant
Spectral type
–
Fomalhaut, an A3 main-sequence star
33.
Astronomical unit
–
The astronomical unit is a unit of length, roughly the distance from Earth to the Sun. However, that varies as Earth orbits the Sun, from a maximum to a minimum. Originally conceived as the average of Earths aphelion and perihelion, it is now defined as exactly 149597870700 metres, the astronomical unit is used primarily as a convenient yardstick for measuring distances within the Solar System or around other stars. However, it is also a component in the definition of another unit of astronomical length. A variety of symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union used the symbol A for the astronomical unit, in 2006, the International Bureau of Weights and Measures recommended ua as the symbol for the unit. In 2012, the IAU, noting that various symbols are presently in use for the astronomical unit, in the 2014 revision of the SI Brochure, the BIPM used the unit symbol au. In ISO 80000-3, the symbol of the unit is ua. Earths orbit around the Sun is an ellipse, the semi-major axis of this ellipse is defined to be half of the straight line segment that joins the aphelion and perihelion. The centre of the sun lies on this line segment. In addition, it mapped out exactly the largest straight-line distance that Earth traverses over the course of a year, knowing Earths shift and a stars shift enabled the stars distance to be calculated. But all measurements are subject to some degree of error or uncertainty, improvements in precision have always been a key to improving astronomical understanding. Improving measurements were continually checked and cross-checked by means of our understanding of the laws of celestial mechanics, the expected positions and distances of objects at an established time are calculated from these laws, and assembled into a collection of data called an ephemeris. NASAs Jet Propulsion Laboratory provides one of several ephemeris computation services, in 1976, in order to establish a yet more precise measure for the astronomical unit, the IAU formally adopted a new definition. Equivalently, by definition, one AU is the radius of an unperturbed circular Newtonian orbit about the sun of a particle having infinitesimal mass. As with all measurements, these rely on measuring the time taken for photons to be reflected from an object. However, for precision the calculations require adjustment for such as the motions of the probe. In addition, the measurement of the time itself must be translated to a scale that accounts for relativistic time dilation
Astronomical unit
–
Transits of Venus across the face of the Sun were, for a long time, the best method of measuring the astronomical unit, despite the difficulties (here, the so-called " black drop effect ") and the rarity of observations.
Astronomical unit
–
The red line indicates the Earth-Sun distance, which is on average about 1 astronomical unit.
34.
Main sequence
–
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung, Stars on this band are known as main-sequence stars or dwarf stars. These are the most numerous true stars in the universe, after a star has formed, it generates thermal energy in the dense core region through nuclear fusion of hydrogen atoms into helium. During this stage of the lifetime, it is located along the main sequence at a position determined primarily by its mass. All main-sequence stars are in equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere, the energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both. The main sequence is divided into upper and lower parts. Stars below about 1.5 times the mass of the Sun primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the main sequence, the nuclear fusion process mainly uses atoms of carbon. Below this mass, stars have cores that are entirely radiative with convective zones near the surface, with decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an layer of hydrogen. In general, the more massive a star is, the shorter its lifespan on the main sequence, after the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, more massive stars can explode as a supernova, or collapse directly into a black hole. In the early part of the 20th century, information about the types and distances of stars became more readily available, the spectra of stars were shown to have distinctive features, which allowed them to be categorized. Annie Jump Cannon and Edward C, pickering at Harvard College Observatory developed a method of categorization that became known as the Harvard Classification Scheme, published in the Harvard Annals in 1901. In Potsdam in 1906, the Danish astronomer Ejnar Hertzsprung noticed that the reddest stars—classified as K and M in the Harvard scheme—could be divided into two distinct groups and these stars are either much brighter than the Sun, or much fainter. To distinguish these groups, he called them giant and dwarf stars, the following year he began studying star clusters, large groupings of stars that are co-located at approximately the same distance
Main sequence
–
The Sun is the most familiar example of a main-sequence star
Main sequence
–
Hot and brilliant O-type main-sequence stars in star-forming regions. These are all regions of star formation that contain many hot young stars including several bright stars of spectral type O.
35.
Cosmic distance ladder
–
The cosmic distance ladder is the succession of methods by which astronomers determine the distances to celestial objects. A real direct distance measurement of an object is possible only for those objects that are close enough to Earth. The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at distances and methods that work at larger distances. Several methods rely on a candle, which is an astronomical object that has a known luminosity. The ladder analogy arises because no single technique can measure distances at all ranges encountered in astronomy, instead, one method can be used to measure nearby distances, a second can be used to measure nearby to intermediate distances, and so on. Each rung of the ladder provides information that can be used to determine the distances at the next higher rung, at the base of the ladder are fundamental distance measurements, in which distances are determined directly, with no physical assumptions about the nature of the object in question. The precise measurement of stellar positions is part of the discipline of astrometry, direct distance measurements are based upon the astronomical unit, which is the distance between the Earth and the Sun. Historically, observations of transits of Venus were crucial in determining the AU, in the first half of the 20th century, observations of asteroids were also important. Keplers laws provide precise ratios of the sizes of the orbits of objects orbiting the Sun, radar is used to measure the distance between the orbits of the Earth and of a second body. From that measurement and the ratio of the two sizes, the size of Earths orbit is calculated. The Earths orbit is known with a precision of a few meters, the most important fundamental distance measurements come from trigonometric parallax. As the Earth orbits the Sun, the position of stars will appear to shift slightly against the more distant background. These shifts are angles in a triangle, with 2 AU making the base leg of the triangle. The amount of shift is small, measuring 1 arcsecond for an object at the 1 parsec distance of the nearest stars. Astronomers usually express distances in units of parsecs, light-years are used in popular media, because parallax becomes smaller for a greater stellar distance, useful distances can be measured only for stars whose parallax is larger than a few times the precision of the measurement. Parallax measurements typically have an accuracy measured in milliarcseconds, the Hubble telescope WFC3 now has the potential to provide a precision of 20 to 40 microarcseconds, enabling reliable distance measurements up to 5,000 parsecs for small numbers of stars. By the early 2020s, the GAIA space mission will provide similarly accurate distances to all bright stars. Stars have a velocity relative to the Sun that causes proper motion, for a group of stars with the same spectral class and a similar magnitude range, a mean parallax can be derived from statistical analysis of the proper motions relative to their radial velocities
Cosmic distance ladder
–
Light green boxes: Technique applicable to star-forming galaxies.
Cosmic distance ladder
–
Statue of an astronomer and the concept of the cosmic distance ladder by the parallax method, made from the azimuth ring and other parts of the Yale–Columbia Refractor (telescope) (c 1925) wrecked by the 2003 Canberra bushfires which burned out the Mount Stromlo Observatory; at Questacon, Canberra, Australian Capital Territory
Cosmic distance ladder
–
SN 1994D (bright spot on the lower left) in the NGC 4526 galaxy. Image by NASA, ESA, The Hubble Key Project Team, and The High-Z Supernova Search Team
Cosmic distance ladder
–
Galaxy cluster
36.
Asteroseismology
–
Asteroseismology is the study of oscillations in stars. Asteroseismology is closely related to helioseismology, the study of stellar oscillations specifically in the Sun, though both are based on the same underlying physics, more and qualitatively different information is available for the Sun because its surface can be resolved. In non-rotating stars, modes with the same angular degree must all have the same frequency because there is no preferred axis. The angular degree indicates the number of lines on the stellar surface, so for large values of ℓ. As a consequence, modes can only be detected up to a degree of about 3 in intensity. The last two are defined by N2 = g and S ℓ2 = ℓ c s 2 r 2 respectively. By analogy with the behaviour of simple harmonic oscillators, this implies that oscillating solutions exist when the frequency is greater or less than both S ℓ and N. We identify the former case as high-frequency pressure modes and the latter as low-frequency gravity modes and this basic separation allows us to determine where we expect what kind of mode to resonate in a star. By plotting the curves ω = N and ω = S ℓ, κ -mechanism Under fairly specific conditions, some stars have regions where heat is transported by radiation and the opacity is a sharply decreasing function of temperature. This opacity bump can drive oscillations through the κ -mechanism, suppose that, at the beginning of an oscillation cycle, the stellar envelope has contracted. By expanding and cooling slightly, the layer in the opacity bump becomes more opaque, absorbs more radiation and this heating causes expansion, further cooling and the layer becomes even more opaque. This continues until the material opacity stops increasing so rapidly, at point the radiation trapped in the layer can escape. The star contracts and the cycle prepares to commence again, in this sense, the opacity acts like a valve that traps heat in the stars envelope. Pulsations driven by the κ -mechanism are coherent and have relatively large amplitudes and it drives the pulsations in many of the longest-known variable stars, including the Cepheid and RR Lyrae variables. In stars with surface convection zones, turbulent fluids motions near the surface simultaneously excite, because the modes are intrinsically stable, they have low amplitudes and are relatively short-lived. This is the mechanism in all solar-like oscillators. This mechanism is known as blocking and is believed to drive pulsations in the γ Doradus variables. Observations from the Kepler satellite revealed eccentric binary systems in which oscillations are excited during the closest approach and these systems are known as heartbeat stars because of the characteristic shape of the lightcurves
Asteroseismology
–
Different oscillation modes penetrate to different depths inside a star.
37.
A-type main-sequence star
–
An A-type main-sequence star or A dwarf star is a main-sequence star of spectral type A and luminosity class V. These stars have spectra which are defined by strong hydrogen Balmer absorption lines. They have masses from 1.4 to 2.1 times the mass of the Sun and surface temperatures between 7600 and 11500 K. Bright and nearby examples are Altair, Sirius A, and Vega. The revised Yerkes Atlas system listed a dense grid of A-type dwarf spectral standard stars, the seminal review of MK classification by Morgan & Keenan did not provide any dagger standards between types A3 V and F2 V. HD23886 was suggested as an A5 V standard in 1978. Richard Gray & Robert Garrison provided the most recent contributions to the A dwarf spectral sequence in a pair of papers in 1987 and 1989. They list an assortment of fast- and slow-rotating A-type dwarf spectral standards, including HD45320, HD88955,2 Hydri,21 Leonis Minoris, and 44 Ceti. Besides the MK standards provided in Morgans papers and the Gray & Garrison papers, there are no published A6 V and A8 V standard stars. A-type stars are young and many emit infrared radiation beyond what would be expected from the star alone and this IR excess is attributable to dust emission from a debris disk where planets form. Surveys indicate massive planets commonly form around A-type stars although these planets are difficult to detect using the Doppler spectroscopy method. This is because A-type stars typically rotate very quickly, which makes it difficult to measure the small Doppler shifts induced by orbiting planets since the spectral lines are very broad. However, this type of massive star eventually evolves into a red giant which rotates more slowly. As of early 2011 about 30 Jupiter class planets have been found around evolved K-giant stars including Pollux, Gamma Cephei and Iota Draconis. Doppler surveys around a variety of stars indicate about 1 in 6 stars having twice the mass of the Sun are orbited by one or more Jupiter-sized planets. A-type stars known to have planets include Fomalhaut, HD15082, Beta Pictoris, stellar classification Star count, survey of stars
A-type main-sequence star
–
An artist's impression of Sirius A and Sirius B. Sirius A, an A-type main-sequence star, is the larger of the two.
38.
Red giant
–
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large, the appearance of the red giant is from yellow-orange to red, including the spectral types K and M, but also class S stars and most carbon stars. The most common red giants are stars on the red-giant branch that are still fusing hydrogen into helium in a shell surrounding an inert helium core. Red giants are stars that have exhausted the supply of hydrogen in their cores and have begun thermonuclear fusion of hydrogen in a shell surrounding the core and they have radii tens to hundreds of times larger than that of the Sun. However, their outer envelope is lower in temperature, giving them a reddish-orange hue, despite the lower energy density of their envelope, red giants are many times more luminous than the Sun because of their great size. Among the asymptotic-giant-branch stars belong the carbon stars of type C-N and late C-R, produced when carbon, the first dredge-up occurs during hydrogen shell burning on the red-giant branch, but does not produce a large carbon abundance at the surface. The second, and sometimes third, dredge up occurs during helium shell burning on the asymptotic-giant branch, the stellar limb of a red giant is not sharply-defined, contrary to their depiction in many illustrations. Rather, due to the low mass density of the envelope, such stars lack a well-defined photosphere. The coolest red giants have complex spectra, with lines, emission features. Red giants are evolved from main-sequence stars with masses in the range from about 0.3 M☉ to around 8 M☉, when a star initially forms from a collapsing molecular cloud in the interstellar medium, it contains primarily hydrogen and helium, with trace amounts of metals. These elements are all uniformly mixed throughout the star, the star reaches the main sequence when the core reaches a temperature high enough to begin fusing hydrogen and establishes hydrostatic equilibrium. Over its main sequence life, the star slowly converts the hydrogen in the core into helium, for the Sun, the main-sequence lifetime is approximately 10 billion years. More-massive stars burn disproportionately faster and so have a lifetime than less massive stars. When the star exhausts the hydrogen fuel in its core, nuclear reactions can no longer continue and this brings additional hydrogen into a zone where the temperature and pressure are adequate to cause fusion to resume in a shell around the core. The higher temperatures lead to increasing rates, enough to increase the stars luminosity by a factor of 1. The outer layers of the star then expand greatly, thus beginning the red-giant phase of the stars life, in actuality, though, the color usually is orange. At this time, the star is said to be ascending the red-giant branch of the Hertzsprung–Russell diagram, the outer layers carry the energy evolved from fusion to the surface by way of convection. This causes material exposed to nuclear burning in the interior to be brought to the stars surface for the first time in its history
Red giant
–
Mira, a red giant
Red giant
–
Hertzsprung–Russell diagram
Red giant
–
This image tracks the life of a Sun -like star, from its birth on the left side of the frame to its evolution into a red giant on the right after billions of years.
Red giant
–
Mira A is an old star, already shedding its outer layers into space.
39.
Helium flash
–
A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low mass stars during their red giant phase. A much rarer runaway helium fusion process can occur on the surface of accreting white dwarf stars. Low mass stars do not produce enough pressure to initiate normal helium fusion. This increases the density and temperature of the core until it reaches approximately 100 million kelvin, in main sequence stars, thermal expansion regulates the core temperature, but in degenerate cores this does not occur. Helium fusion increases the temperature, which increases the fusion rate and this produces a flash of very intense helium fusion that lasts only a few minutes, but briefly emits energy at a rate comparable to the entire Milky Way galaxy. Thus the helium flash is mostly undetectable to observation, and is described solely by astrophysical models, after the cores expansion and cooling, the stars surface rapidly cools and contracts until it is roughly 2% of its former radius and luminosity. It is estimated that the helium core weighs about 40% of the star mass. During the red giant phase of evolution in stars with less than 2.0 M☉ the nuclear fusion of hydrogen ceases in the core as it is depleted. Thus the thermal pressure from fusion is no longer sufficient to counter the gravitational collapse and this causes the star to start contracting and increasing in temperature until it eventually becomes compressed enough for the helium core to become degenerate matter. The explosive nature of the helium flash arises from its place in degenerate matter. However, since degeneracy pressure is dominating thermal pressure, the pressure is only weakly dependent on temperature. Thus, the increase in temperature only causes a slight increase in pressure. The core can then expand and cool down and a burning of helium will continue. A star with mass greater than about 2.25 M☉ starts to burn helium without its core becoming degenerate, in a very low-mass star, the core is never hot enough to ignite helium. The degenerate helium core will keep on contracting, and finally becomes a white dwarf. The helium flash is not directly observable on the surface by electromagnetic radiation, the flash occurs in the core deep inside the star, and the net effect will be that all released energy is absorbed by the entire core, leaving the degenerate state to become nondegenerate. Earlier computations indicated that a mass loss would be possible in some cases. This hydrogen can build up to form a shell near the surface of the star, when the mass of hydrogen becomes sufficiently large, runaway fusion causes a nova
Helium flash
–
Small white dwarf star undergoing a helium flash.
Helium flash
–
Fusion of helium in the core of low mass stars.
40.
R Coronae Borealis variable
–
An R Coronae Borealis variable is an eruptive variable star that varies in luminosity in two modes, one low amplitude pulsation, and one irregular unpredictably sudden fading by 1 to 9 magnitudes. The prototype star R Coronae Borealis was discovered by the English amateur astronomer Edward Pigott in 1795, since then, only about 100 RCB variables have been identified, making this class a very rare kind of star. The fading is caused by condensation of carbon to soot, making the star fade in visible light while measurements in infrared light exhibit no real luminosity decrease. R Coronae Borealis variables are typically supergiant stars in the spectral classes F and G, with typical C2 and CN molecular bands, there is a considerable variation in spectrum between various RCB specimens. Most of the stars with known spectrum are either F to G class supergiants, three of the stars are however of the blue B type, for example VZ Sagittarii. Four stars are unusually and inexplicably poor in iron absorption lines in the spectrum, the constant features are prominent Carbon lines, strong atmospheric Hydrogen deficiencies, and obviously the intermittent fadings. The DY Persei variables have been considered a sub-class of R CrB variable, although they are less luminous carbon-rich AGB stars, the 20 radii model requires a large and thereby long-time buildup of the obstructing dust cloud, making the fast light decline hard to comprehend. The formation of the stars themselves is also unclear, standard stellar evolution models do not produce large luminous stars with essentially zero hydrogen. The two main theories to explain these stars are both somewhat exotic, perhaps befitting such rare stars, in one, a merger occurs between two white dwarf stars, one a Helium white dwarf and the other a carbon-oxygen white dwarf. White dwarfs are naturally lacking in hydrogen and the resultant star would also lack that element and it is possible that the diversity of R CrB stars is caused by a diversity of formation mechanisms, relating them to extreme helium stars and hydrogen-deficient carbon stars. This list contains all the R CrB stars listed in the GCVS, DY Persei is not included although it may be a related type of variable. Clayton, from SAO/NASA Astrophysics Data System Variable Star of the Month, January,2000, R Coronae Borealis, at the AAVSO website
R Coronae Borealis variable
–
An AAVSO light curve of fadings by R Coronae Borealis, the prototype star
41.
Red dwarf
–
In May 2015, it was announced that Series XI and XII would film back-to-back later in 2015 and would air exclusively on the Dave channel in 2016 and 2017. The first episode of Red Dwarf XI aired at 9 p. m. on Thursday 22 September 2016 on Dave and has been available via streaming service UKTV Play from Thursday 15 September 2016, the series was created by Rob Grant and Doug Naylor. Despite the pastiche of science fiction used as a backdrop, Red Dwarf is primarily a character-driven comedy, the main characters are Dave Lister, the last known human alive, and Arnold Rimmer, a hologram of Listers dead bunkmate. The series attracted its highest ratings, of more than eight million viewers, the series was revived after a ten-year break, when digital channel Dave screened a three-episode production, titled Red Dwarf, Back to Earth, in April 2009 during the Easter weekend. This was followed by Series X, consisting of six episodes, the show has been critically acclaimed, and has a Metacritic score of 84/100. Series XI was voted Best Returning TV Sitcom and Comedy of the Year for 2016 by readers for the British Comedy Guide. The show was based on Dave Hollins, Space Cadet, a series of five sketches that aired in the BBC Radio 4 series Son of Cliché, produced by Rob Grant and Doug Naylor in 1984. The sketches recounted the adventures of Dave Hollins, a space traveller who is marooned in space far from earth. His only steady companion is the computer Hab, Grant and Naylor chose to use the Dave Hollins, Space Cadet sketches as a base for a television show after watching the 1974 film Dark Star. They changed some elements from the sketches, The 7 trillion year figure was first changed to 7 billion years and then to 3 million and the characters of Arnold Rimmer and the Cat were created. The name Dave Hollins was changed to Dave Lister when a player called Dave Hollins became well-known. One of the actors from Son of Cliché, Chris Barrie went on to portray Arnold Rimmer in the Red Dwarf TV series. Episodes of Dave Hollins can be found on the 2-disc Red Dwarf DVD sets starting with series 5 and ending with series 8. The main setting of the series is the eponymous mining spaceship Red Dwarf, which is 6 miles long,4 miles tall, following the accident, the ships computer Holly keeps Lister in stasis until the radiation levels return to normal – a process that takes three million years. Lister therefore emerges as the last human being in the universe – and his former bunkmate and immediate superior Arnold Judas Rimmer is resurrected by Holly as a hologram to keep Lister sane. During the second series, the encounter the service mechanoid Kryten. Initially, Kryten only appeared in one episode of two, but by the beginning of series three he had become a regular character. A complicated series of events leaves Kochanski stranded in the main universe
Red dwarf
–
The second Red Dwarf ship model as used for series 5.
Red dwarf
Red dwarf
–
From left to right: Kryten, Lister, Cat, and Rimmer as they appeared in 2009's Back to Earth.
Red dwarf
–
The episode " Polymorph " parodied the 1979 Alien film
42.
Nova
–
A nova or classical nova is an astronomical event that causes the sudden appearance of a bright new star, that slowly fades from view over several weeks or many months. Novae should not be confused with more energetic astronomical phenomena known as supernovae. Several main sub-classes of novae exist, based on their many different scenarios, being classical novae, recurrent novae, dwarf novae and they are together under a group of variable stars collectively known as cataclysmic variable stars, which share some common properties as close binary systems. Classical novae eruptions are the most common type of novae and they are likely created in a close binary star system consisting of a white dwarf and either a main sequence, sub-giant or red giant star. This mostly hydrogen atmosphere is heated from the hot white dwarf star, which eventually reaches a critical temperature. A few novae produce short-lived nova remnants, lasting several centuries. Recurrent nova processes are the same as the classical nova, except that the ignition can be repeated because the companion star can again feed the dense atmosphere of the white dwarf. Occurrences of novae mostly occur in the sky along the path of the Milky Way, however, it is also quite possibly for them to appear anywhere in the sky. They are far more frequent than galactic supernovae, presently averaging about ten per year, the majority are found telescopically, with few reaching naked-eye visibility, perhaps averaging about once every year to eighteen months. Novae reaching 1st or 2nd magnitude occur only several times per century, the last bright nova was V1369 Centauri reaching 3.3 magnitude on 14 December 2013. During the 16th century, astronomer Tycho Brahe observed the supernova SN1572 in the constellation Cassiopeia and he described it in his book De nova stella, giving rise to the name nova. In this work he argued that an object should be seen to move relative to the fixed stars. Though this was a supernova and not a nova, the terms were considered interchangeable until the 1930s, after this, novae were classified as classical novae to distinguishing them from supernovae, as their causes and energies were though to be different based soley in the observational evidence. Evolution of potential novae begins with two main stars in a binary system. One of the two evolves into a red giant leaving its remnant white dwarf core in orbit with the remaining star, the second star—which may be either a main sequence star or an aging giant—begins to shed its envelope onto its white dwarf companion when it overflows its Roche lobe. As a result, the white dwarf captures matter in an accretion disk steadily from the outer atmosphere. As the white dwarf consists of matter, so the accreted hydrogen does not inflate. Rapid, an all at once, uncontrolled fusion occurs when the temperature of this layer reaches ~20 million Kelvins
Nova
–
Artist's conception of a white dwarf accreting hydrogen from a larger companion
Nova
–
GK Persei: Nova of 1901
Nova
–
Nova Eridani 2009 (apparent magnitude ~8.4) during a full moon
Nova
–
Messier 31 Image by NASA
43.
Astrophysical X-ray source
–
Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays. Some solar system bodies emit X-rays, the most notable being the Moon, a combination of many unresolved X-ray sources is thought to produce the observed X-ray background. Furthermore, celestial entities in space are discussed as celestial X-ray sources, the origin of all observed astronomical X-ray sources is in, near to, or associated with a coronal cloud or gas at coronal cloud temperatures for however long or brief a period. Clusters of galaxies are formed by the merger of smaller units of matter, the infalling material gains kinetic energy as it falls into the clusters gravitational potential well. The infalling gas collides with gas already in the cluster and is heated to between 107 and 108 K depending on the size of the cluster. This very hot gas emits X-rays by thermal emission. The galaxies and dark matter are collisionless and quickly become virialised, a quasi-stellar radio source is a very energetic and distant galaxy with an active galactic nucleus. QSO 0836+7107 is a Quasi-Stellar Object that emits baffling amounts of radio energy and this radio emission is caused by electrons spiraling along magnetic fields producing cyclotron or synchrotron radiation. These electrons can interact with visible light emitted by the disk around the AGN or the black hole at its center. These photons accelerate the electrons, which then emit X- and gamma-radiation via Compton, on board the Compton Gamma Ray Observatory is the Burst and Transient Source Experiment which detects in the 20 keV to 8 MeV range. QSO 0836+7107 or 4C71.07 was detected by BATSE as a source of gamma rays. What BATSE has discovered is that it can be a soft gamma-ray source, QSO 0836+7107 is the faintest and most distant object to be observed in soft gamma rays. It has already observed in gamma rays by the Energetic Gamma Ray Experiment Telescope also aboard the Compton Gamma Ray Observatory. Seyfert galaxies are a class of galaxies with nuclei that produce spectral line emission from highly ionized gas and they are a subclass of active galactic nuclei, and are thought to contain supermassive black holes. The following early-type galaxies have been observed to be X-ray bright due to hot gaseous coronae,315,1316,1332,1395,2563,4374,4382,4406,4472,4594,4636,4649, and 5128. The X-ray emission can be explained as thermal bremsstrahlung from hot gas, ultraluminous X-ray sources are pointlike, nonnuclear X-ray sources with luminosities above the Eddington limit of 3 ×1032 W for a 20 M☉ black hole. Many ULXs show strong variability and may be black hole binaries, to fall into the class of intermediate-mass black holes, their luminosities, thermal disk emissions, variation timescales, and surrounding emission-line nebulae must suggest this. However, when the emission is beamed or exceeds the Eddington limit, the nearby spiral galaxy NGC1313 has two compact ULXs, X-1 and X-2
Astrophysical X-ray source
–
X-rays start at ~0.008 nm and extend across the electromagnetic spectrum to ~8 nm, over which Earth's atmosphere is opaque.
Astrophysical X-ray source
–
X-ray photo by Chandra X-ray Observatory of the Bullet Cluster. Exposure time was 140 hours. The scale is shown in mega parsecs. Redshift (z) = 0.3, meaning its light has wavelengths stretched by a factor of 1.3.
Astrophysical X-ray source
–
A view of 4C 71.07 from observations by the Burst and Transient Source Experiment. This helped convince scientists that they were studying data from the quasar and not some other source in the neighborhood.
Astrophysical X-ray source
–
Chandra image of Cygnus X-1, which was the first strong black hole candidate to be discovered.
44.
ROSAT
–
ROSAT was a German Aerospace Center-led satellite X-ray telescope, with instruments built by West Germany, the United Kingdom and the United States. It was launched on 1 June 1990, on a Delta II rocket from Cape Canaveral, on what was designed as an 18-month mission. ROSAT actually operated for eight years, finally shutting down on 12 February 1999. Parts as heavy as 400 kg could impact the surface intact, ROSAT eventually re-entered the Earths atmosphere on 23 October 2011. According to NASA, the Roentgensatellit was a joint German, U. S. ROSAT carried a German-built imaging X-ray Telescope with three focal plane instruments, two German Position Sensitive Proportional Counters and the US-supplied High Resolution Imager. The X-ray mirror assembly was a grazing incidence four-fold nested Wolter I telescope with an 84-cm diameter aperture, the angular resolution was less than 5 arcsecond at half energy width. The XRT assembly was sensitive to X-rays between 0.1 and 2 keV, in addition, a British-supplied extreme ultraviolet telescope, the Wide Field Camera, was coaligned with the XRT and covered the energy band from 0.042 to 0.21 keV. ROSATs unique strengths were high resolution, low-background, soft X-ray imaging for the study of the structure of low surface brightness features. ROSAT was capable of fast slews which makes it possible to observe two targets on opposite hemispheres during each orbit, the pointing accuracy was 1 arcminute with stability less than 5 arcsec per sec and jitter radius of ~10 arcsec. Two CCD star sensors were used for position sensing of guide stars. The post facto attitude determination accuracy was 6 arcsec, the survey was carried out in the scan mode. The second phase consists of the remainder of the mission and was devoted to pointed observations of selected astrophysical sources, in ROSATs pointed phase, observing time was allocated to Guest Investigators from all three participating countries through peer review of submitted proposals. ROSAT had a life of 18 months, but was expected to operate beyond its nominal lifetime. The main assembly was a German-built imaging X-ray Telescope with three focal plane instruments, two German Position Sensitive Proportional Counters and the US-supplied High Resolution Imager. The X-ray mirror assembly was a grazing incidence four-fold nested Wolter I telescope with an 84 cm diameter aperture and 240 cm focal length, the angular resolution was less than 5 arcsec at half energy width. The XRT assembly was sensitive to X-rays between 0.1 and 2 keV, each Position Sensitive Proportional Counter is a thin-window gas counter. Each incoming X-ray photon produces an electron cloud whose position and charge are detected using two wire grids, the photon position is determined with an accuracy of about 120 micrometers. The electron clouds charge corresponds to the photon energy, the US supplied High Resolution Imager used a crossed grid detector with a position accuracy to 25 micrometers
ROSAT
–
Launch of the ROSAT in Cape Canaveral, Florida.
ROSAT
–
ROSAT: one of the last images of ROSAT before reentry
45.
Brown dwarf
–
Below this range are the sub-brown dwarfs, and above it are the lightest red dwarfs. Brown dwarfs may be fully convective, with no layers or chemical differentiation by depth, unlike the stars in the main-sequence, brown dwarfs are not massive enough to sustain nuclear fusion of ordinary hydrogen to helium in their cores. They are, however, thought to fuse deuterium and to fuse lithium if their mass is above a threshold of 13 MJ and 65 MJ. It is also debated whether brown dwarfs would be defined by their formation processes rather than by their supposed nuclear fusion reactions. Stars are categorized by spectral class, with brown dwarfs designated as types M, L, T, despite their name, brown dwarfs are of different colors. Many brown dwarfs would likely appear magenta to the human eye, Brown dwarfs are not very luminous at visible wavelengths. Planets are known to orbit some brown dwarfs, 2M1207b, MOA-2007-BLG-192Lb, at a distance of about 6.5 light years, the nearest known brown dwarf is Luhman 16, a binary system of brown dwarfs discovered in 2013. DENIS-P J082303. 1-491201 b is listed as the known exoplanet in NASAs exoplanet archive. However, a) the term black dwarf was already in use to refer to a white dwarf, b) red dwarfs fuse hydrogen. Because of this, alternate names for these objects were proposed, in 1975, Jill Tarter suggested the term brown dwarf, using brown as an approximate color. The term black dwarf still refers to a dwarf that has cooled to the point that it no longer emits significant light. The first self-consistent calculation of the minimum mass confirmed a value between 0.08 and 0.07 solar masses for population I objects. The discovery of deuterium burning down to 0.012 solar masses, however, such objects were hard to find as they emit almost no visible light. Their strongest emissions are in the spectrum, and ground-based IR detectors were too imprecise at that time to readily identify any brown dwarfs. Since then, numerous searches by various methods have sought these objects, for many years, efforts to discover brown dwarfs were fruitless. In 1988, however, a faint companion to a known as GD165 was found in an infrared search of white dwarfs. The spectrum of the companion GD 165B was very red and enigmatic and it became clear that GD 165B would need to be classified as a much cooler object than the latest M dwarfs then known. GD 165B remained unique for almost a decade until the advent of the Two Micron All Sky Survey which discovered many objects with similar colors, today, GD 165B is recognized as the prototype of a class of objects now called L dwarfs
Brown dwarf
–
Artist's concept of a T-type brown dwarf
Brown dwarf
–
Comparision: most brown dwarfs are only slightly larger than Jupiter (10–15%) but up to 75 times heavier due to greater density. Note: The Sun is not to scale and would be larger.
Brown dwarf
–
The smaller object is Gliese 229B, about 20 to 50 times the mass of Jupiter, orbiting the star Gliese 229. It is in the constellation Lepus, about 19 light years from Earth.
Brown dwarf
–
A size comparison between the Sun, a young sub-brown dwarf, and Jupiter. As the sub-brown dwarf ages, it will gradually cool and shrink.
46.
Wide-field Infrared Survey Explorer
–
Wide-field Infrared Survey Explorer is a NASA infrared-wavelength astronomical space telescope launched in December 2009, and placed in hibernation in February 2011 when its transmitter turned off. WISE discovered thousands of planets and numerous star clusters. Its observations also supported the discovery of the first Y Dwarf, WISE performed an all-sky astronomical survey with images in 3.4,4.6,12 and 22 μm wavelength range bands, over ten months using a 40 cm diameter infrared telescope in Earth orbit. After its hydrogen coolant depleted, a mission extension called NEOWISE was conducted to search for near-Earth objects such as comets. The All-Sky data including processed images, source catalogs and raw data, was released to the public on March 14,2012, in August 2013, NASA announced it would reactivate the WISE telescope for a new three-year mission to search for asteroids that could collide with Earth. Science operations and data processing for WISE and NEOWISE take place at the Infrared Processing, the mission was planned to create infrared images of 99 percent of the sky, with at least eight images made of each position on the sky in order to increase accuracy. The spacecraft was placed in a 525 km, circular, polar, Sun-synchronous orbit for its mission, during which it has taken 1.5 million images. Each image covers a 47-arcminute field of view, which means a 6-arcsecond resolution, each area of the sky was scanned at least 10 times at the equator, the poles were scanned at theoretically every revolution due to the overlapping of the images. The produced image library contains data on the local Solar System, the Milky Way, among the objects WISE studied are asteroids, cool, dim stars such as brown dwarfs, and the most luminous infrared galaxies. Stellar nurseries, which are covered by interstellar dust, are detectable in infrared, Infrared measurements from the WISE astronomical survey have been particularly effective at unveiling previously undiscovered star clusters. Examples of such embedded star clusters are Camargo 18, Camargo 440, Majaess 101, in addition, galaxies of the young Universe and interacting galaxies, where star formation is intensive, are bright in infrared. On this wavelength the interstellar gas clouds are also detectable, as well as proto-planetary discs, WISE satellite was expected to find at least 1,000 of those proto-planetary discs. WISE was not able to detect Kuiper belt objects, because their temperatures are too low and it was able to detect any objects warmer than 70–100 K. A Neptune-sized object would be out to 700 AU, a Jupiter-mass object out to 1 light year. A larger object of 2–3 Jupiter masses would be visible at a distance of up to 7–10 light years and that translates to about 1000 new main-belt asteroids per day, and 1–3 NEOs per day. The peak of magnitude distribution for NEOs will be about 21–22 V, WISE would detect each typical Solar System object 10–12 times over about 36 hours in intervals of 3 hours. Construction of the WISE telescope was divided between Ball Aerospace & Technologies, SSG Precision Optronics, Inc, DRS and Rockwell, Lockheed Martin, and Space Dynamics Laboratory. The program was managed through the Jet Propulsion Laboratory, the WISE instrument was built by the Space Dynamics Laboratory in Logan, Utah
Wide-field Infrared Survey Explorer
–
Artist concept of WISE spacecraft
Wide-field Infrared Survey Explorer
Wide-field Infrared Survey Explorer
–
Comet C/2007 Q3 (Siding Spring) in infrared by WISE
Wide-field Infrared Survey Explorer
–
A scaffolding structure built around WISE allows engineers access while its hydrogen coolant is being frozen
47.
Star formation
–
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as stellar nurseries or star-forming regions, fuse to form stars. It is closely related to formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a star, must also account for the statistics of binary stars. In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z =6.60, a spiral galaxy like the Milky Way contains stars, stellar remnants, and a diffuse interstellar medium of gas and dust. The interstellar medium consists of 10−4 to 106 particles per cm3 and is composed of roughly 70% hydrogen by mass. This medium has been enriched by trace amounts of heavier elements that were ejected from stars as they passed beyond the end of their main sequence lifetime. Higher density regions of the interstellar medium form clouds, or diffuse nebulae, in the dense nebulae where stars are produced, much of the hydrogen is in the molecular form, so these nebulae are called molecular clouds. These giant molecular clouds have densities of 100 particles per cm3, diameters of 100 light-years, masses of up to 6 million solar masses. About half the mass of the galactic ISM is found in molecular clouds and in the Milky Way there are an estimated 6,000 molecular clouds. The nearest nebula to the Sun where massive stars are being formed is the Orion nebula,1,300 ly away, however, lower mass star formation is occurring about 400–450 light years distant in the ρ Ophiuchi cloud complex. A more compact site of formation is the opaque clouds of dense gas and dust known as Bok globules. These can form in association with collapsing molecular clouds or possibly independently, the Bok globules are typically up to a light year across and contain a few solar masses. They can be observed as dark clouds silhouetted against bright emission nebulae or background stars, over half the known Bok globules have been found to contain newly forming stars. An interstellar cloud of gas will remain in equilibrium as long as the kinetic energy of the gas pressure is in balance with the potential energy of the internal gravitational force. Mathematically this is expressed using the theorem, which states that, to maintain equilibrium. If a cloud is massive enough that the gas pressure is insufficient to support it, the mass above which a cloud will undergo such collapse is called the Jeans mass. The Jeans mass depends on the temperature and density of the cloud and this coincides with the typical mass of an open cluster of stars, which is the end product of a collapsing cloud. In triggered star formation, one of several events occur to compress a molecular cloud
Star formation
–
Star formation
Star formation
–
Hubble telescope image known as Pillars of Creation, where stars are forming in the Eagle Nebula.
Star formation
–
Assembly of galaxy in early Universe.
Star formation
–
Stellar cluster and star-forming region M 17.
48.
Barred spiral galaxy
–
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in approximately two-thirds of all spiral galaxies, bars generally affect both the motions of stars and interstellar gas within spiral galaxies and can affect spiral arms as well. The Milky Way Galaxy, where our own Solar System is located, is classified as a spiral galaxy. Edwin Hubble classified spiral galaxies of this type as SB in his Hubble sequence, sBa types feature tightly bound arms, while SBc types are at the other extreme and have loosely bound arms. SB0 is a lenticular galaxy. Among other types in Hubbles classifications for the galaxies are, spiral galaxy, elliptical galaxy, Barred galaxies are apparently predominant, with surveys showing that up to two-thirds of all spiral galaxies contain a bar. The current hypothesis is that the bar structure acts as a type of stellar nursery, the bar is thought to act as a mechanism that channels gas inwards from the spiral arms through orbital resonance, in effect funneling the flow to create new stars. This process is thought to explain why many barred spiral galaxies have active galactic nuclei. The creation of the bar is thought to be the result of a density wave radiating from the center of the galaxy whose effects reshape the orbits of the inner stars. This effect builds over time to stars orbiting further out, which creates a bar structure. Bars are thought to be temporary phenomena in the lives of spiral galaxies, past a certain size the accumulated mass of the bar compromises the stability of the overall bar structure. Barred spiral galaxies with high mass accumulated in their center tend to have short, since so many spiral galaxies have bar structures, it is likely that they are recurring phenomena in spiral galaxy development. The oscillating evolutionary cycle from spiral galaxy to barred spiral galaxy is thought to take on the average about two billion years, recent studies have confirmed the idea that bars are a sign of galaxies reaching full maturity as the formative years end. The sub-categories are based on how open or tight the arms of the spiral are, sBa types feature tightly bound arms. SBc types are at the extreme and have loosely bound arms. SBm describes somewhat irregular barred spirals, sB0 is a barred lenticular galaxy. Galaxy morphological classification Galaxy formation and evolution Lenticular galaxy Spiral galaxy Firehose instability Britt, Milky Way’s Central Structure Seen with Fresh Clarity. An article about the Spitzer Space Telescopes Milky Way discovery Devitt, galactic survey reveals a new look for the Milky Way
Barred spiral galaxy
–
NGC 1300, viewed nearly face-on; Hubble Space Telescope image
Barred spiral galaxy
–
Milky Way Galaxy Spiral Arms - based on WISE data.
Barred spiral galaxy
–
NGC 2787
Barred spiral galaxy
–
NGC 4314
49.
Telescope
–
A telescope is an optical instrument that aids in the observation of remote objects by collecting electromagnetic radiation. The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s and they found use in both terrestrial applications and astronomy. Within a few decades, the telescope was invented, which used mirrors to collect. In the 20th century many new types of telescopes were invented, including radio telescopes in the 1930s, the word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors. The word telescope was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galileis instruments presented at a banquet at the Accademia dei Lincei, in the Starry Messenger, Galileo had used the term perspicillum. The earliest recorded working telescopes were the telescopes that appeared in the Netherlands in 1608. Their development is credited to three individuals, Hans Lippershey and Zacharias Janssen, who were spectacle makers in Middelburg, Galileo heard about the Dutch telescope in June 1609, built his own within a month, and improved upon the design in the following year. Also in 1609, Thomas Harriot became the first person known to point a telescope skyward in order to make observations of a celestial object. The idea that the objective, or light-gathering element, could be a mirror instead of a lens was being investigated soon after the invention of the refracting telescope. The potential advantages of using parabolic mirrors—reduction of spherical aberration and no chromatic aberration—led to many proposed designs, in 1668, Isaac Newton built the first practical reflecting telescope, of a design which now bears his name, the Newtonian reflector. The invention of the lens in 1733 partially corrected color aberrations present in the simple lens and enabled the construction of shorter. The largest reflecting telescopes currently have objectives larger than 10 m, the 20th century also saw the development of telescopes that worked in a wide range of wavelengths from radio to gamma-rays. The first purpose built radio telescope went into operation in 1937, since then, a tremendous variety of complex astronomical instruments have been developed. The name telescope covers a range of instruments. Most detect electromagnetic radiation, but there are differences in how astronomers must go about collecting light in different frequency bands. The near-infrared can be collected much like light, however in the far-infrared and submillimetre range. For example, the James Clerk Maxwell Telescope observes from wavelengths from 3 μm to 2000 μm, on the other hand, the Spitzer Space Telescope, observing from about 3 μm to 180 μm uses a mirror. Also using reflecting optics, the Hubble Space Telescope with Wide Field Camera 3 can observe in the range from about 0.2 μm to 1.7 μm
Telescope
–
The 100 inch (2.54 m) Hooker reflecting telescope at Mount Wilson Observatory near Los Angeles, USA.
Telescope
–
Modern telescopes typically use CCDs instead of film for recording images. This is the sensor array in the Kepler spacecraft.
Telescope
–
28-inch telescope and 40-foot telescope in Greenwich in 2015.
Telescope
–
50 cm refracting telescope at Nice Observatory.
50.
Radio galaxy
–
Radio galaxies and their relatives, radio-loud quasars and blazars, are types of active galaxy that are very luminous at radio wavelengths, with luminosities up to 1039 W between 10 MHz and 100 GHz. The radio emission is due to the synchrotron process, the observed structure in radio emission is determined by the interaction between twin jets and the external medium, modified by the effects of relativistic beaming. The host galaxies are almost exclusively large elliptical galaxies, radio-loud active galaxies can be detected at large distances, making them valuable tools for observational cosmology. Recently, much work has been done on the effects of objects on the intergalactic medium, particularly in galaxy groups. The radio emission from radio-loud active galaxies is synchrotron emission, as inferred from its smooth, broad-band nature. This implies that the plasma contains, at least, electrons with relativistic speeds. Since the plasma must be neutral, it must also contain either protons or positrons, there is no way of determining the particle content directly from observations of synchrotron radiation. A sister process to the radiation is the inverse-Compton process, in which the relativistic electrons interact with ambient photons. This has been used to argue that many sources are actually quite near the minimum-energy condition. In the latter case the electrons must have energies in excess of 1 TeV in typical magnetic field strengths. Again, polarization and continuum spectrum are used to distinguish the synchrotron radiation from other emission processes, jets and hotspots are the usual sources of high-frequency synchrotron emission. It is hard to distinguish observationally between the synchrotron and inverse-Compton radiation, making them a subject of ongoing research, processes, collectively known as particle acceleration, produce populations of relativistic and non-thermal particles that give rise to synchrotron and inverse-Compton radiation. Fermi acceleration is one plausible particle acceleration process in radio-loud active galaxies, radio galaxies, and to a lesser extent, radio-loud quasars display a wide range of structures in radio maps. The most common structures are called lobes, these are double, often fairly symmetrical. A significant minority of low-luminosity sources exhibit structures usually known as plumes which are more elongated. Some radio galaxies show one or two long narrow features known as coming directly from the nucleus and going to the lobes. Since the 1970s, the most widely accepted model has been that the lobes or plumes are powered by beams of high-energy particles and magnetic field coming from close to the active nucleus. The jets are believed to be the manifestations of the beams
Radio galaxy
51.
Active galactic nucleus
–
Such excess non-stellar emission has been observed in the radio, microwaves, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy, the radiation from an AGN is believed to be a result of accretion of matter by a supermassive black hole at the center of its host galaxy. Numerous subclasses of AGN have been defined based on their observed characteristics, early photographic observations of nearby galaxies detected some characteristic signatures of AGN emission, although there was not yet a physical understanding of the nature of the AGN phenomenon. Further spectroscopic studies by astronomers including Vesto Slipher, Milton Humason, in 1943, Carl Seyfert published a paper in which he described observations of nearby galaxies having bright nuclei that were sources of unusually broad emission lines. Galaxies observed as part of study included NGC1068, NGC4151, NGC3516. Active galaxies such as these are known as Seyfert galaxies in honor of Seyferts pioneering work, the development of radio astronomy was a major catalyst to understanding AGN. Some of the earliest detected radio sources are nearby active elliptical galaxies such as Messier 87, the 3C radio survey led to further progress in discovery of new radio sources as well as identifying the visible-light sources associated with the radio emission. In photographic images, some of these objects were nearly point-like or quasi-stellar in appearance, a major breakthrough was the measurement of the redshift of the quasar 3C273 by Maarten Schmidt, published in 1963. Shortly afterward, optical spectra were used to measured the redshifts of a number of quasars including 3C48. The enormous luminosities of these quasars as well as their unusual spectral properties indicated that their power source could not be ordinary stars, Accretion of gas onto a supermassive black hole was suggested as the source of quasars power in papers by Edwin Salpeter and Yakov ZelDovich in 1964. Today, AGN are a topic of astrophysical research, both observational and theoretical. For a long time it has argued that an AGN must be powered by accretion of mass onto massive black holes. AGN are both compact and persistently extremely luminous, thus AGN-like characteristics are expected whenever a supply of material for accretion comes within the sphere of influence of the central black hole. In the standard model of AGN, cold material close to a black hole forms an accretion disc, dissipative processes in the accretion disc transport matter inwards and angular momentum outwards, while causing the accretion disc to heat up. The radiation from the accretion disc excites cold atomic material close to the black hole, a large fraction of the AGNs radiation may be obscured by interstellar gas and dust close to the accretion disc, but this will be re-radiated at some other waveband, most likely the infrared. Some accretion discs produce jets of twin, highly collimated, the direction of the jet ejection is determined either by the angular momentum axis of the accretion disc or the spin axis of the black hole. The jet production mechanism and indeed the jet composition on very small scales are not understood at present due to the resolution of astronomical instruments being too low, there exists a class of radiatively inefficient solutions to the equations that govern accretion. The most widely known of these is the Advection Dominated Accretion Flow, radiatively inefficient AGN would be expected to lack many of the characteristic features of standard AGN with an accretion disc
Active galactic nucleus
–
Image taken by the Hubble Space Telescope of a 5000 light-year long jet ejected from the active galaxy M87. The blue synchrotron radiation contrasts with the yellow starlight from the host galaxy.
Active galactic nucleus
–
Unification by viewing angle. From bottom to top: down the jet - Blazar, at an angle to the jet - Quasar / Seyfert 1 Galaxy, at 90 degrees from the jet - Radio galaxy / Seyfert 2 Galaxy
52.
Seyfert galaxy
–
Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. They have quasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines and these galaxies have supermassive black holes at their centers which are surrounded by accretion discs of in-falling material. The accretion discs are believed to be the source of the ultraviolet radiation. Ultraviolet emission and absorption lines provide the best diagnostics for the composition of the surrounding material, Seyfert galaxies are named after Carl Seyfert, who first described this class in 1943. They noticed that NGC1068 showed six bright emission lines, which was considered unusual as most objects observed showed a spectrum corresponding to stars. In 1926, Edwin Hubble looked at the lines of NGC1068. In 1943, Carl Keenan Seyfert discovered more galaxies similar to NGC1068, in 1944 Cygnus A was detected at 160 MHz, and detection was confirmed in 1948 when it was established that it was a discrete source. Its double radio structure became apparent with the use of interferometry, in the next few years, other radio sources such as supernova remnants were discovered. In the 1960-1970s, research to understand the properties of Seyfert galaxies was carried out. Controversy existed over whether Seyfert redshifts were of cosmological origin, in the same time period, research had been undertaken to survey, identify and catalogue galaxies, including Seyferts. At the time, it was believed that 1% of spiral galaxies are Seyferts, by 1977, it was found that very few Seyfert galaxies are ellipticals, most of them being normal or barred spiral galaxies. During the same period, efforts have been made to gather spectrophotometric data for Seyfert galaxies. It became obvious that not all spectra from Seyfert galaxies look the same, a simple division into types I and II has been devised, with the classes depending on the relative width of their emission lines. It has been noticed that some Seyfert nuclei show intermediate properties. Early surveys for Seyfert galaxies were biased in counting only the brightest representatives of this group, Seyfert galaxies form a substantial fraction of the galaxies appearing in the Markarian catalog, a list of galaxies displaying an ultraviolet excess in their nuclei. An active galactic nucleus is a region at the center of a galaxy that has a higher than normal luminosity over portions of the electromagnetic spectrum. A galaxy having a nucleus is called an active galaxy. Active galactic nuclei are the most luminous sources of radiation in the Universe
Seyfert galaxy
–
The Circinus Galaxy, a Type II Seyfert galaxy
Seyfert galaxy
–
NGC 1068 (Messier 77), one of the first Seyfert galaxies classified
Seyfert galaxy
–
NGC 5793 is a Seyfert galaxy located over 150 million light-years away in the constellation of Libra.
Seyfert galaxy
–
Optical and ultraviolet images of the black hole in the center of NGC 4151, a Seyfert Galaxy
53.
Henry Norris Russell
–
Henry Norris Russell was an American astronomer who, along with Ejnar Hertzsprung, developed the Hertzsprung–Russell diagram. In 1923, working with Frederick Saunders, he developed Russell–Saunders coupling which is known as LS coupling. Russell was born in 1877 in Oyster Bay, New York and he studied astronomy at Princeton University, obtaining his B. A. In 1897 and his doctorate in 1899, studying under Charles Augustus Young, from 1903 to 1905, he worked at the Cambridge Observatory with Arthur Robert Hinks as a research assistant of the Carnegie Institution and came under the strong influence of George Darwin. He returned to Princeton to become an instructor in astronomy, assistant professor, professor and he was also the director of the Princeton University Observatory from 1912 to 1947. He died in Princeton, New Jersey in 1957 at the age of 79, in November 1908 Russell married Lucy May Cole. Their youngest daughter, Margaret, married the astronomer Frank K. Edmondson in the 1930s, Russell co-wrote an influential two-volume textbook in 1927 with Raymond Smith Dugan and John Quincy Stewart, Astronomy, A Revision of Young’s Manual of Astronomy. This became the standard textbook for about two decades. There were two volumes, the first was The Solar System and the second was Astrophysics and Stellar Astronomy, the textbook popularized the idea that a stars properties were largely determined by the stars mass and chemical composition, which became known as the Vogt-Russell theorem. Since a stars chemical composition changes with age, stellar evolution results. However, he changed his mind four years later after deriving the same result by different means, after Payne was proven correct, Russell briefly credited Payne for discovering that the Sun had a different chemical composition from Earth in his paper. However the credit was given to him instead. Henry Norris Russell, Frederick Albert Saunders, New Regularities in the Spectra of the Alkaline Earths. Henry Norris Russell, Raymond Smith Dugan, John Quincy Stewart, Astronomy, A Revision of Young’s Manual of Astronomy, Vol. I, The Solar System, Vol. II, Astrophysics and Stellar Astronomy. Boston, Ginn & Co. Henry Norris Russell, on the Composition of the Suns Atmosphere
Henry Norris Russell
–
Henry Norris Russell
54.
Sky & Telescope
–
The articles are intended for the informed lay reader and include detailed discussions of current discoveries, frequently by participating scientists. The magazine is illustrated in color, with both amateur and professional photography of celestial sights, as well as tables and charts of upcoming celestial events. In 2005, Sky Publishing Corporation was acquired by New Track Media, in 2014, New Track was sold to F+W Media. The magazine played an important role in the dissemination of knowledge about telescope making, Amateur astronomy Amateur telescope making Official website
Sky & Telescope
–
The front cover of the March 2005 issue.
55.
ArXiv
–
In many fields of mathematics and physics, almost all scientific papers are self-archived on the arXiv repository. Begun on August 14,1991, arXiv. org passed the half-million article milestone on October 3,2008, by 2014 the submission rate had grown to more than 8,000 per month. The arXiv was made possible by the low-bandwidth TeX file format, around 1990, Joanne Cohn began emailing physics preprints to colleagues as TeX files, but the number of papers being sent soon filled mailboxes to capacity. Additional modes of access were added, FTP in 1991, Gopher in 1992. The term e-print was quickly adopted to describe the articles and its original domain name was xxx. lanl. gov. Due to LANLs lack of interest in the rapidly expanding technology, in 1999 Ginsparg changed institutions to Cornell University and it is now hosted principally by Cornell, with 8 mirrors around the world. Its existence was one of the factors that led to the current movement in scientific publishing known as open access. Mathematicians and scientists regularly upload their papers to arXiv. org for worldwide access, Ginsparg was awarded a MacArthur Fellowship in 2002 for his establishment of arXiv. The annual budget for arXiv is approximately $826,000 for 2013 to 2017, funded jointly by Cornell University Library, annual donations were envisaged to vary in size between $2,300 to $4,000, based on each institution’s usage. As of 14 January 2014,174 institutions have pledged support for the period 2013–2017 on this basis, in September 2011, Cornell University Library took overall administrative and financial responsibility for arXivs operation and development. Ginsparg was quoted in the Chronicle of Higher Education as saying it was supposed to be a three-hour tour, however, Ginsparg remains on the arXiv Scientific Advisory Board and on the arXiv Physics Advisory Committee. The lists of moderators for many sections of the arXiv are publicly available, additionally, an endorsement system was introduced in 2004 as part of an effort to ensure content that is relevant and of interest to current research in the specified disciplines. Under the system, for categories that use it, an author must be endorsed by an established arXiv author before being allowed to submit papers to those categories. Endorsers are not asked to review the paper for errors, new authors from recognized academic institutions generally receive automatic endorsement, which in practice means that they do not need to deal with the endorsement system at all. However, the endorsement system has attracted criticism for allegedly restricting scientific inquiry, perelman appears content to forgo the traditional peer-reviewed journal process, stating, If anybody is interested in my way of solving the problem, its all there – let them go and read about it. The arXiv generally re-classifies these works, e. g. in General mathematics, papers can be submitted in any of several formats, including LaTeX, and PDF printed from a word processor other than TeX or LaTeX. The submission is rejected by the software if generating the final PDF file fails, if any image file is too large. ArXiv now allows one to store and modify an incomplete submission, the time stamp on the article is set when the submission is finalized
ArXiv
–
arXiv
ArXiv
–
A screenshot of the arXiv taken in 1994, using the browser NCSA Mosaic. At the time, HTML forms were a new technology.
56.
Astrophysics and Space Science
–
Astrophysics and Space Science is a bimonthly peer-reviewed scientific journal covering astronomy, astrophysics, and space science and astrophysical aspects of astrobiology. It was established in 1968 and is published by Springer Science+Business Media, the editor-in-chief is Michael A. Dopita. The journal is abtracted and indexed in the databases, According to the Journal Citation Reports
Astrophysics and Space Science
–
Astrophysics and Space Science
57.
J. Davy Kirkpatrick
–
J. Davy Kirkpatrick is an American astronomer at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, California. Kirkpatricks research was named one of the top ten science accomplishments of the first ten years of the W. M. Keck Observatory, Kirkpatrick received a BS in mathematics and physics/astronomy from Vanderbilt University in 1986 and a PhD in astronomy from the University of Arizona in 1992. Much of Kirkpatricks research has concentrated on the discovery and characterization of the lowest mass stars, along with Neill Reid, he uncovered many objects similar to and colder than GD 165B, leading to the definition of the L dwarf spectral class. Also using 2MASS data, he and graduate student Adam Burgasser discovered brown dwarfs even colder than spectral class L, along with Adam Burgasser and Chris Gelino, Kirkpatrick maintains a listing of all known L, T, and Y dwarf discoveries at the DwarfArchives website. Kirkpatrick is credited with first using the name Tyche to refer to a heretofore unseen and he chose this term to be in direct contrast to Nemesis, an unseen Solar companion hypothesized to lie in a highly elliptical orbit and to be responsible for periodic mass extinctions on the Earth. Kirkpatricks own search using the 2MASS data set out any Solar companion more massive than 30 Jupiter masses. New Spectral Types L and T from Annual Review of Astronomy and Astrophysics,2005 M Dwarfs and L Dwarfs, Chapter 9 of Stellar Spectral Classification 2011 Wendell G
J. Davy Kirkpatrick
–
J. Davy Kirkpatrick
58.
Apus
–
Apus is a small constellation in the southern sky. It represents a bird-of-paradise, and its name means without feet in Greek because the bird-of-paradise was once believed to lack feet. First depicted on a celestial globe by Petrus Plancius in 1598, the French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations in 1756. The five brightest stars are all reddish in hue, shading the others at apparent magnitude 3.8 is Alpha Apodis, an orange giant that has around 48 times the diameter and 928 times the luminosity of the Sun. Marginally fainter is Gamma Apodis, another ageing giant star, Delta Apodis is a double star, the two components of which are 103 arcseconds apart and visible with the naked eye. Two star systems have found to have planets. It first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius, Apis is presumably a typographical error for avis. After its introduction on Planciuss globe, the constellations first known appearance in an atlas was in German cartographer Johann Bayers Uranometria of 1603. Bayer called it Apis Indica while fellow astronomers Johannes Kepler and his son-in-law Jakob Bartsch called it Apus or Avis Indica, the name Apus is derived from the Greek apous, meaning without feet. This referred to the Western misconception that the bird-of-paradise had no feet, such specimens began to arrive in Europe in 1522, when the survivors of Ferdinand Magellans expedition brought them home. The constellation later lost some of its tail when Nicolas-Louis de Lacaille used those stars to establish Octans in the 1750s, covering 206.3 square degrees and hence 0. 5002% of the sky, Apus ranks 67th of the 88 modern constellations by area. Its position in the Southern Celestial Hemisphere means that the constellation is visible to observers south of 7°N. It is bordered by Ara, Triangulum Australe and Circinus to the north, Musca and Chamaeleon to the west, Octans to the south, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Aps. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of six segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 13h 49. 5m and 18h 27. 3m, while the coordinates are between −67. 48° and −83. 12°. Lacaille gave twelve stars Bayer designations, labelling them Alpha through to Kappa, within the constellations borders, there are 39 stars brighter than or equal to apparent magnitude 6.5. Beta, Gamma and Delta Apodis form a triangle, with Alpha Apodis lying to the east. The five brightest stars are all red-tinged, which is unusual among constellations, Alpha Apodis is an orange giant of spectral type K3III located 447 ±8 light years away from Earth, with an apparent magnitude of 3.8
Apus
–
The constellation Apus as it can be seen by the naked eye.
Apus
–
List of stars in Apus
Apus
–
Globular cluster IC 4499 taken by Hubble Space Telescope.
59.
Aquila (constellation)
–
Aquila is a constellation on the celestial equator. Its name is Latin for eagle and it represents the bird who carried Zeus/Jupiters thunderbolts in Greco-Roman mythology and its brightest star, Altair, is one vertex of the Summer Triangle asterism. The constellation is best seen in the summer as it is located along the Milky Way. Because of this location along the line of our Galaxy, many clusters and nebulae are found within its borders, Aquila was one of the 48 constellations described by the 2nd century astronomer Ptolemy. It had been mentioned by Eudoxus in the 4th century BC. It is now one of the 88 constellations defined by the International Astronomical Union, the constellation was also known as Vultur volans to the Romans, not to be confused with Vultur cadens which was their name for Lyra. It is often held to represent the eagle who held Zeuss/Jupiters thunderbolts in Greco-Roman mythology, Aquila is also associated with the eagle who kidnapped Ganymede, a son of one of the kings of Troy, to Mount Olympus to serve as cup-bearer to the gods. Hevelius determined twenty-three stars in the first and nineteen in the second, the Greek Aquila is probably based on the Babylonian constellation of the Eagle, which is located in the same area as the Greek constellation. Aquila, which lies in the Milky Way, contains many rich starfields and has been the location of many novae, α Aql is the brightest star in this constellation and one of the closest naked-eye stars to Earth at a distance of 17 light-years. Its name comes from the Arabic phrase al-nasr al-tair, meaning the flying eagle, Altair has a magnitude of 0.76. β Aql is a star of magnitude 3.7,45 light-years from Earth. Its name comes from the Arabic phrase shahin-i tarazu, meaning the balance, this referred to Altair, Alshain. γ Aql is a giant star of magnitude 2.7,460 light-years from Earth. Its name, like that of Alshain, comes from the Arabic for the balance, ζ Aql is a blue-white-hued star of magnitude 3.0,83 light-years from Earth. η Aql is a supergiant star,1200 light-years from Earth. Among the brightest Cepheid variable stars, it has a magnitude of 4.4. 15 Aql is a double star. The primary is a giant of magnitude 5.4,325 light-years from Earth
Aquila (constellation)
–
The constellation Aquila as it can be seen by the naked eye.
Aquila (constellation)
–
List of stars in Aquila
Aquila (constellation)
–
The former constellation Antinous was merged into Aquilla in 1930, but both can be seen in this 1825 chart from Urania's Mirror.
Aquila (constellation)
–
IRAS 19024+0044 is a protoplanetary nebula in Aquila.
60.
Ara (constellation)
–
Ara is a southern constellation situated between Scorpius and Triangulum Australe. Ara was one of the 48 Greek constellations described by the 2nd century astronomer Ptolemy, the orange supergiant Beta Arae is the brightest star in the constellation, with an apparent magnitude of 2. 85—marginally brighter than the blue-white Alpha Arae. The sunlike star Mu Arae hosts four planets, while Gliese 676 is a red dwarf system with four planets. The Milky Way crosses the northwestern part of Ara, in ancient Greek mythology, Ara was identified as the altar where the gods first made offerings and formed an alliance before defeating the Titans. The nearby Milky Way represents the rising from the offerings on the altar. It had been recorded by Aratus in 270 BCE as lying close to the horizon, professor of astronomy Bradley Schaefer has proposed that ancient observers must have been able to see as far south as Zeta Arae to define a pattern that looked like an altar. In illustrations, Ara is usually depicted as an altar with its smoke rising southward, however, depictions of Ara often vary in their details. In the early days of printing, a 1482 woodcut of Gaius Julius Hyginuss classic Poeticon Astronomicon depicts the altar as surrounded by demons, johann Bayer in 1603 depicted Ara as an altar with burning incense, the flames rise southward as in most atlases. Hyginus also depicted Ara as an altar with burning incense, though his Ara featured devils on either side of the flames. However, Willem Blaeu, a Dutch uranographer active in the 16th and 17th centuries, drew Ara as a designed for sacrifice. Unlike most depictions, the smoke from Blaeus Ara rises northward, in Chinese astronomy, the stars of the constellation Ara lie within The Azure Dragon of the East. Five stars of Ara formed Guī, a tortoise, while another three formed Chǔ, a pestle, covering 237.1 square degrees and hence 0. 575% of the sky, Ara ranks 63rd of the 88 modern constellations by area. Its position in the Southern Celestial Hemisphere means that the constellation is visible to observers south of 22°N. Scorpius runs along the length of its border, while Norma and Triangulum Australe line it to the west, Apus to the south. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union, is Ara, the official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of twelve segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 16h 36. 1m and 18h 10. 4m, while the coordinates are between −45. 49° and −67. 69°. Bayer gave eight stars Bayer designations, labelling them Alpha through to Theta, after charting the southern constellations, Lacaille recharted the stars of Ara from Alpha though to Sigma, including three pairs of stars next to each other as Epsilon, Kappa and Nu. Ara contains part of the Milky Way to the south of Scorpius and thus has rich star fields, within the constellations borders, there are 71 stars brighter than or equal to apparent magnitude 6.5
Ara (constellation)
–
The constellation Ara as it can be seen by the naked eye.
Ara (constellation)
–
List of stars in Ara
Ara (constellation)
–
Johann Elert Bode 's illustration of Ara, from his Uranographia (1801)
61.
Aries (constellation)
–
Aries is one of the constellations of the zodiac. It is located in the celestial hemisphere between Pisces to the west and Taurus to the east. The name Aries is Latin for ram, and its symbol is and it is one of the 48 constellations described by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations. It is a constellation, ranking 39th overall size, with an area of 441 square degrees. Although Aries came to represent specifically the ram whose fleece became the Golden Fleece of Ancient Greek mythology, before that, the stars of Aries formed a farmhand. Different cultures have incorporated the stars of Aries into different constellations including twin inspectors in China, Aries is a relatively dim constellation, possessing only four bright stars, Hamal, Sheratan, Mesarthim, and 41 Arietis. The few deep-sky objects within the constellation are faint and include several pairs of interacting galaxies. Several meteor showers appear to radiate from Aries, including the Daytime Arietids, Aries is now recognized as an official constellation, albeit as a specific region of the sky, by the International Astronomical Union. It was originally defined in ancient texts as a pattern of stars. In the description of the Babylonian zodiac given in the clay tablets known as the MUL. APIN, the MUL. APIN was a comprehensive table of the risings and settings of stars, which likely served as an agricultural calendar. Modern-day Aries was known as MULLÚ. ḪUN. GÁ, The Agrarian Worker or The Hired Man, the earliest identifiable reference to Aries as a distinct constellation comes from the boundary stones that date from 1350 to 1000 BC. On several boundary stones, a zodiacal ram figure is distinct from the characters present. The shift in identification from the constellation as the Agrarian Worker to the Ram likely occurred in later Babylonian tradition because of its association with Dumuzi the Shepherd. By the time the MUL. APIN was created—by 1000 BC—modern Aries was identified with both Dumuzis ram and a hired laborer, the exact timing of this shift is difficult to determine due to the lack of images of Aries or other ram figures. In ancient Egyptian astronomy, Aries was associated with the god Amon-Ra, because it was the location of the vernal equinox, it was called the Indicator of the Reborn Sun. During the times of the year when Aries was prominent, priests would process statues of Amon-Ra to temples, Aries acquired the title of Lord of the Head in Egypt, referring to its symbolic and mythological importance. Aries was not fully accepted as a constellation until classical times, in Hellenistic astrology, the constellation of Aries is associated with the golden ram of Greek mythology that rescued Phrixos and Helle on orders from Hermes, taking Phrixos to the land of Colchis. Phrixos and Helle were the son and daughter of King Athamas, the kings second wife, Ino, was jealous and wished to kill his children
Aries (constellation)
–
Aries and Musca Borealis as depicted in Urania's Mirror, a set of constellation cards published in London c.1825
Aries (constellation)
–
List of stars in Aries
Aries (constellation)
–
The constellation Aries as it can be seen with the naked eye
Aries (constellation)
–
NGC 772, with a notated supernova.
62.
Auriga (constellation)
–
Auriga is one of the 88 modern constellations, it was among the 48 constellations listed by the 2nd-century astronomer Ptolemy. Located north of the equator, its name is the Latin word for charioteer, associating it with various mythological charioteers. Auriga is most prominent during winter evenings in the northern Hemisphere, because of its northern declination, Auriga is only visible in its entirety as far as 34° south, for observers farther south it lies partially or fully below the horizon. A large constellation, with an area of 657 square degrees, it is half the size of the largest constellation and its brightest star, Capella, is an unusual multiple star system among the brightest stars in the night sky. Beta Aurigae is a variable star in the constellation, Epsilon Aurigae. Because of its position near the winter Milky Way, Auriga has many open clusters in its borders, including M36, M37. In addition, it has one prominent nebula, the Flaming Star Nebula, in Chinese mythology, Aurigas stars were incorporated into several constellations, including the celestial emperors chariots, made up of the modern constellations brightest stars. Auriga is home to the radiant for the Aurigids, Zeta Aurigids, Delta Aurigids, the first record of Aurigas stars was in Mesopotamia as a constellation called GAM, representing a scimitar or crook. However, this may have represented just Capella or the constellation as a whole. The crook of Auriga stood for a goat-herd or shepherd and it was formed from most of the stars of the modern constellation, all of the bright stars were included except for Elnath, traditionally assigned to both Taurus and Auriga. Later, Bedouin astronomers created constellations that were groups of animals, the stars of Auriga comprised a herd of goats, an association also present in Greek mythology. The association with goats carried into the Greek astronomical tradition, though it became associated with a charioteer along with the shepherd. In Greek mythology, Auriga is often identified as the mythological Greek hero Erichthonius of Athens and his chariot was created in the image of the Suns chariot, the reason Zeus placed him in the heavens. The Athenian hero then dedicated himself to Athena and, soon after, Zeus raised him into the sky in honor of his ingenuity. Auriga, however, is described as Myrtilus, who was Hermess son. The association of Auriga and Myrtilus is supported by depictions of the constellation, Myrtiluss chariot was destroyed in a race intended for suitors to win the heart of Oenomauss daughter Hippodamia. Myrtilus earned his position in the sky when Hippodamias successful suitor, Pelops, killed him, after his death, Myrtiluss father Hermes placed him in the sky. Yet another mythological association of Auriga is Theseuss son Hippolytus and he was ejected from Athens after he refused the romantic advances of his stepmother Phaedra, who committed suicide as a result
Auriga (constellation)
–
A painting by Peter Paul Rubens entitled Finding of Erichthonius; Erichthonius and Auriga are often associated.
Auriga (constellation)
–
List of stars in Auriga
Auriga (constellation)
–
Auriga carrying the goat and kids as depicted in Urania's Mirror, a set of constellation cards illustrated by Sidney Hall, London circa 1825.
Auriga (constellation)
–
The constellation Auriga as it can be seen by the naked eye.
63.
Caelum
–
Caelum /ˈsiːləm/ is a faint constellation in the southern sky, introduced in the 1750s by Nicolas Louis de Lacaille and counted among the 88 modern constellations. Its name means “chisel” in Latin, and it was known as Caelum Scalptorium, It is a rare word, unrelated to the far more common Latin caelum, meaning “sky, heaven. It is the eighth-smallest constellation, and subtends an angle of around 0.038 steradians. Due to its size and location away from the plane of the Milky Way, Caelum is a rather barren constellation. The constellations brightest star, Alpha Caeli, is only of magnitude 4.45, Caelum was first introduced in the eighteenth century by Nicolas Louis de Lacaille, a French astronomer who introduced thirteen other southern constellations at the same time. Lacaille gave the constellation the French name Burin, which was originally Latinized to Caelum Scalptorium, francis Baily shortened this name to Caelum, as suggested by John Herschel. In Lacailles original chart, the constellation was shown both as a burin and an échoppe, although it has come to be recognized simply as a chisel. Johann Elert Bode stated the name as plural with a singular possessor, Caela Scalptoris – in German Grabstichel –, Caelum is bordered by Dorado and Pictor to the south, Horologium and Eridanus to the east, Lepus to the north, and Columba to the west. Covering only 125 square degrees, it ranks 81st of the 88 modern constellations in size and it appears prominently in the southern sky during the Southern Hemispheres summer, and the whole constellation is visible for at least part of the year to observers south of latitude 41°N. Its main asterism consists of four stars, and twenty stars in total are brighter than magnitude 6.5, the constellation’s boundaries, as set by Eugène Delporte in 1930, are defined by a 12-sided polygon. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 04h 19. 5m and 05h 05. 1m, while the coordinates are between −27. 02° and −48. 74°. The International Astronomical Union adopted the three-letter abbreviation “Cae” for the constellation in 1922, Caelum is a faint constellation, It has no star brighter than magnitude 4 and only two stars brighter than magnitude 5. Lacaille gave six stars Bayer designations, labeling them Alpha to Zeta in 1756, Bode extended the designations to Rho for other stars, but most of these have fallen out of use. Caelum is too far south for any of its stars to bear Flamsteed designations. The brightest star, α Caeli, is a star, containing an F-type main-sequence star of magnitude 4.45. β Caeli, another F-type star of magnitude 5.05, is further away, unlike α, β Caeli is a subgiant star, slightly evolved from the main sequence. δ Caeli, also of magnitude 5.05, is a B-type subgiant and is farther from Earth. γ1 Caeli is a double-star with a red giant primary of magnitude 4.58, the primary is 55.59 parsecs from Earth
Caelum
–
Seen as "Cela Sculptoris" in the lower right of this 1825 star chart from Urania's Mirror
Caelum
–
List of stars in Caelum
Caelum
–
The constellation Caelum as it can be seen by the naked eye.
Caelum
–
The Seyfert galaxy HE0450-2958, an unusual active galaxy in Caelum
64.
Carina (constellation)
–
Carina /kəˈraɪnə/ is a constellation in the southern sky. Carina was once a part of Argo Navis, the ship of Jason. The constellation of Argo was introduced in ancient Greece, however, Nicolas Louis de Lacaille divided Argo into three component constellations in 1763, including Carina, the Keel. Despite the division, Lacaille kept Argos Bayer designations, therefore, Carina has the α, β and ε, Vela has γ and δ, Puppis has ζ, and so on. Carina contains Canopus, a white-hued supergiant that is the second brightest star in the sky at magnitude −0.72,313 light-years from Earth. Alpha Carinae, as Canopus is formally designated, is a star that varies by approximately 0.1 magnitudes. Its traditional name comes from the mythological Canopus, who was a navigator for Menelaus, there are several other stars above magnitude 3 in Carina. Beta Carinae, traditionally called Miaplacidus, is a blue-white hued star of magnitude 1.7,111 light-years from Earth, Epsilon Carinae is an orange-hued giant star similarly bright to Miaplacidus at magnitude 1.9, it is 630 light-years from Earth. Another fairly bright star is the blue-white hued Theta Carinae, it is a magnitude 2.7 star 440 light-years from Earth, Theta Carinae is also the most prominent member of the cluster IC2602. Iota Carinae is a supergiant star of magnitude 2.2,690 light-years from Earth. Eta Carinae is the most prominent variable star in Carina, with a mass of approximately 100 solar masses and 4 million times as bright as the Sun. It was first discovered to be unusual in 1677, when its magnitude suddenly rose to 4, Eta Carinae is inside NGC3372, commonly called the Carina Nebula. It had a long outburst in 1827, when it brightened to magnitude 1 and its most prominent outburst made Eta Carinae the equal of Sirius, it brightened to magnitude −1.5 in 1843. However, since 1843, Eta Carinae has remained relatively placid, however, in 1998, it brightened again, though only to magnitude 5.0, a far less drastic outburst. Eta Carinae is a star, with a companion that has a period of 5.5 years. There are several less prominent variable stars in Carina, L Carinae is a Cepheid variable noted for its brightness, it is the brightest Cepheid that is variable to the unaided eye. It is a supergiant star with a minimum magnitude of 4.2. Two bright Mira variable stars are in Carina, R Carinae and S Carinae, R Carinae has a minimum magnitude of 10.0 and a maximum magnitude of 4.0
Carina (constellation)
–
The constellation Carina as it can be seen by the naked eye
Carina (constellation)
–
List of stars in Carina
65.
Chamaeleon
–
Chamaeleon is a small constellation in the southern sky. It is named after the chameleon, a kind of lizard and it was first defined in the 16th century. Chamaeleon was one of twelve created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser. It first appeared on a 35-cm diameter celestial globe published in 1597 in Amsterdam by Plancius and Jodocus Hondius, johann Bayer was the first uranographer to put Chamaeleon in a celestial atlas. It was one of many created by European explorers in the 15th and 16th centuries out of unfamiliar Southern Hemisphere stars. There are four stars in Chamaeleon. Alpha Chamaeleontis is a star of magnitude 4.1,63 light-years from Earth. Beta Chamaeleontis is a blue-white hued star of magnitude 4.2,27 light-years from Earth, gamma Chamaeleontis is a red-hued giant star of magnitude 4.1,413 light-years from Earth. The other bright star in Chamaeleon is Delta Chamaeleontis, a double star. The brighter star is Delta2 Chamaeleontis, a star of magnitude 4.4,364 light-years from Earth. Delta1 Chamaeleontis, the component, is an orange-hued giant star of magnitude 5.5,354 light-years away. Chamaeleon is also the location of Cha 110913, a dwarf star or proto solar system. In 1999, a open cluster was discovered centered on the star η Chamaeleontis. The cluster, known as either the Eta Chamaeleontis cluster or Mamajek 1, is 8 million years old, the constellation contains a number of molecular clouds that are forming low-mass T Tauri stars. The cloud complex lies some 400 to 600 light years from Earth, the most prominent cluster of T Tauri stars and young B-type stars are in the Chamaeleon I cloud, and are associated with the reflection nebula IC2631. Chamaeleon contains one planetary nebula, NGC3195, which is fairly faint and it appears in a telescope at about the same apparent size as Jupiter. In Chinese astronomy, the stars that form Chamaeleon were classified as the Little Dipper among the Southern Asterisms by Xu Guangqi. W
Chamaeleon
–
The constellation Chamaeleon as it can be seen by the naked eye.
Chamaeleon
–
List of stars in Chamaeleon
66.
Columba (constellation)
–
Columba is a small, faint constellation created in the late sixteenth century. Its name is Latin for dove and it is located just south of Canis Major and Lepus. Columba was created by Dutch astronomer Petrus Plancius in 1592 in order to differentiate the unformed stars of the large constellation Canis Major, Plancius first depicted Columba on the small celestial planispheres of his large wall map of 1592. It is also shown on his world map of 1594. Plancius originally named the constellation Columba Noachi, referring to the dove that gave Noah the information that the Great Flood was receding and this name is found on early 17th-century celestial globes and star atlases. Columba may also represent the dove released by Jason and the Argonauts at the Black Seas mouth, in the Society Islands, Alpha Columbae was called Ana-iva. Columba is rather inconspicuous, the brightest star, Alpha Columbae, Alpha Columbae, a blue-white star, is traditionally called Phact, which means ring dove. Alpha Columbae is 268 light-years from Earth, the only other named star in Columba is Beta Columbae, which has the name Wazn. It is a giant star of magnitude 3.1,86 light-years from Earth. Columba is the constellation that is at the solar antapex - the Earth is moving away from its direction as the system moves through space. The constellation contains the runaway star μ Columbae, which was expelled from the ι Orionis system. There is one cluster in Columba, 7th-magnitude NGC1851. It is 35,000 light-years from Earth and is resolvable in medium-sized amateur telescopes. NGC1792 is a galaxy of magnitude 10.2. NGC1808 is a Seyfert galaxy of magnitude 10.8, the Morning Star Rises, an account of Polynesian astronomy. Ridpath, Ian, Tirion, Wil, Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2 Ian Ridpath, Stars and Planets Guide, Collins, London. Star Tales – Columba Columba Constellation at Constellation Guide
Columba (constellation)
–
The constellation Columba as it can be seen by the naked eye.
Columba (constellation)
–
List of stars in Columba
Columba (constellation)
–
Seen as "Columba Noachi" in Urania's Mirror (1825)
67.
Coma Berenices
–
Coma Berenices is an ancient asterism in the northern sky which has been defined as one of the 88 modern constellations. It is located in the fourth quadrant, between Leo and Bootes, and is visible in both hemispheres. It was introduced to Western astronomy during the third century BC by Conon of Samos and its name means Berenices Hair in Latin and refers to Queen Berenice II of Egypt, who sacrificed her long hair as a votive offering. Coma Berenices is the modern constellation named for an historic figure. It was further corroborated as a constellation by Gerardus Mercator and Tycho Brahe, three of the constellations stars are visible to the naked eye, Alpha Comae Berenices, Beta Comae Berenices and Gamma Comae Berenices. They form a 45-degree triangle, from which Berenices imaginary tresses hang, the constellations brightest star is Beta Comae Berenices, a 4. 2-magnitude main sequence star similar to the Sun. Coma Berenices contains the North Galactic Pole and one of the richest known galaxy clusters, Galaxy Malin 1, in the constellation, is the first known giant low-surface-brightness galaxy. Supernova SN 2005ap discovered in Coma Berenices is the brightest known, the star FK Comae Berenices is the prototype of an eponymous class of variable stars. The constellation is the radiant of one meteor shower, Coma Berenicids, Coma Berenices has been recognized as an asterism since the Hellenistic period, and is the only modern constellation named for an historic figure. It was introduced to Western astronomy during the third century BC by Conon of Samos, Berenice vowed to sacrifice her long hair as a votive offering if Ptolemy returned safely from battle during the Third Syrian War. In Callimachus poem, Aetia, Berenice dedicated her tresses to all the gods, in the Latin translation of the poem by the Roman poet Catullus and in Hyginus De astronomica, she dedicated her tresses to Aphrodite and placed them in the temple of Arsinoe II at Zephyrium. According to De astronomica, by the morning the tresses had disappeared. Conon proposed that Aphrodite had placed the tresses in the sky as an acknowledgement of Berenices sacrifice, Callimachus called the asterism plokamos Berenikēs or bostrukhon Berenikēs in Greek, translated into Latin as Coma Berenices by Catullus. Eratosthenes called it Berenices Hair and Ariadnes Hair, considering it part of the constellation Leo, the astronomer Geminus recognized it as a distinct constellation. Astronomer Ptolemy considered it part of Leo, and called it Plokamos, Coma Berenices became popular during the 16th century. In 1515, a set of gores by Johannes Schöner labelled the asterism Trica, in 1536 it appeared on a celestial globe by Caspar Vopel, who is credited with the asterisms designation as a constellation. That year, it appeared on a celestial map by Petrus Apianus as Crines Berenices. In 1551, Coma Berenices appeared on a celestial globe by Gerardus Mercator with five Latin and Greek names, Cincinnus, caesaries, πλόκαμος, Berenicis crinis, mercators reputation as a cartographer ensured the constellations inclusion on Dutch sky globes beginning in 1589
Coma Berenices
–
Queen Berenice II of Egypt
Coma Berenices
–
List of stars in Coma Berenices
Coma Berenices
–
Plate by Sidney Hall and Richard Rouse Bloxam from Urania's Mirror. Coma Berenices can be seen on the right.
Coma Berenices
–
The constellation Coma Berenices as it can be seen by the naked eye.
68.
Corona Australis
–
Corona Australis or Corona Austrina is a constellation in the Southern Celestial Hemisphere. Its Latin name means southern crown, and it is the counterpart of Corona Borealis. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, the Ancient Greeks saw Corona Australis as a wreath rather than a crown and associated it with Sagittarius or Centaurus. Other cultures have likened the pattern to a turtle, ostrich nest, although fainter than its namesake, the oval- or horseshoe-shaped pattern of its brighter stars renders it distinctive. Alpha and Beta Coronae Australis are the two brightest stars with an apparent magnitude of around 4.1, Epsilon Coronae Australis is the brightest example of a W Ursae Majoris variable in the southern sky. Within it are stars at the earliest stages of their lifespan, the variable stars R and TY Coronae Australis light up parts of the nebula, which varies in brightness accordingly. The name of the constellation was entered as Corona Australis when the International Astronomical Union established the 88 modern constellations in 1922, in 1932, the name was instead recorded as Corona Austrina when the IAUs commission on notation approved a list of four-letter abbreviations for the constellations. Although the four-letter abbreviations were repealed in 1955, this name has persisted alongside the original. The IAU presently uses Corona Australis exclusively, Corona Australis is a small constellation bordered by Sagittarius to the north, Scorpius to the west, Telescopium to the south, and Ara to the southwest. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is CrA, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of four segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 17h 58. 3m and 19h 19. 0m, while the coordinates are between −36. 77° and −45. 52°. Covering 128 square degrees, Corona Australis culminates at midnight around the 30th of June, while not a bright constellation, Corona Australis is nonetheless distinctive due to its easily identifiable pattern of stars, which has been described as horseshoe- or oval-shaped. Though it has no stars brighter than 4th magnitude, it still has 21 stars visible to the unaided eye. Nicolas Louis de Lacaille used the Greek letters Alpha through to Lambda to label the most prominent eleven stars in the constellation, the only star in the constellation to have received a name is Alfecca Meridiana or Alpha CrA. The name combines the Arabic name of the constellation with the Latin for southern, in Arabic, Alfecca means break, and refers to the shape of both Corona Australis and Corona Borealis. Also called simply Meridiana, it is a main sequence star located 130 light years away from Earth, with an apparent magnitude of 4.10. A rapidly rotating star, it spins at almost 200 km per second at its equator, like the star Vega, it has excess infrared radiation, which indicates it may be ringed by a disk of dust. It is currently a star, but will eventually evolve into a white dwarf, currently, it has a luminosity 31 times greater
Corona Australis
–
The constellation Corona Australis as it can be seen by the naked eye.
Corona Australis
–
List of stars in Corona Australis
Corona Australis
Corona Australis
–
Corona Australis depicted in the Atlas Coelestis of John Flamsteed
69.
Corona Borealis
–
Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy and its brightest stars form a semicircular arc. Its Latin name, inspired by its shape, means northern crown, in classical mythology Corona Borealis generally represented the crown given by the god Dionysus to the Cretan princess Ariadne and set by him in the heavens. Other cultures likened the pattern to a circle of elders, an eagles nest, Ptolemy also listed a southern counterpart, Corona Australis, with a similar pattern. The brightest star is the magnitude 2.2 Alpha Coronae Borealis, T Coronae Borealis, also known as the Blaze Star, is another unusual type of variable star known as a recurrent nova. Normally of magnitude 10, it last flared up to magnitude 2 in 1946, ADS9731 and Sigma Coronae Borealis are multiple star systems with six and five components respectively. Five star systems have found to have Jupiter-sized exoplanets. Abell 2065 is a highly concentrated galaxy cluster one billion light-years from the Solar System containing more than 400 members, covering 179 square degrees and hence 0. 433% of the sky, Corona Borealis ranks 73rd of the 88 modern constellations by area. Its position in the Northern Celestial Hemisphere means that the constellation is visible to observers north of 50°S. It is bordered by Boötes to the north and west, Serpens Caput to the south, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is CrB. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of eight segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 15h 16. 0m and 16h 25. 1m, while the coordinates are between 39. 71° and 25. 54°. It has a counterpart—Corona Australis—in the Southern Celestial Hemisphere, the seven stars that make up the constellations distinctive crown-shaped pattern are all 4th-magnitude stars except for the brightest of them, Alpha Coronae Borealis. The other six stars are Theta, Beta, Gamma, Delta, Epsilon, the German cartographer Johann Bayer gave twenty stars in Corona Borealis Bayer designations from Alpha to Upsilon in his 1603 star atlas Uranometria. Zeta Coronae Borealis was noted to be a star by later astronomers and its components designated Zeta1. John Flamsteed did likewise with Nu Coronae Borealis, classed by Bayer as a single star and he named them 20 and 21 Coronae Borealis in his catalogue, alongside the designations Nu1 and Nu2 respectively. Chinese astronomers deemed nine stars to make up the asterism, adding Pi, within the constellations borders, there are 37 stars brighter than or equal to apparent magnitude 6.5. Alpha Coronae Borealis appears as a star of magnitude 2.2
Corona Borealis
–
The constellation Corona Borealis as it can be seen by the naked eye
Corona Borealis
–
List of stars in Corona Borealis
Corona Borealis
–
X-ray image of galaxy cluster Abell 2142
Corona Borealis
–
Hercules and Corona Borealis, as depicted in Urania's Mirror (c. 1825)
70.
Crater (constellation)
–
Crater is a small constellation in the Southern Celestial Hemisphere. Its name means cup in Latin, one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it depicts a cup that has been associated with the god Apollo and is perched on the back of Hydra the water snake. There is no star brighter than third magnitude and its two brightest stars, Delta Crateris of magnitude 3.56 and Alpha Crateris of magnitude 4.07, are ageing orange giant stars that are cooler and larger than the Sun. In the Babylonian star catalogues dating from at least 1100 BCE, john H. Rogers observed that the adjoining constellation Hydra signified Ningishzida, the god of the underworld in the Babylonian compendium MUL. APIN. He proposed that Corvus and Crater were death symbols and marked the gate to the underworld and these two constellations, along with the eagle Aquila and the fish Piscis Austrinus, were introduced to the Greeks around 500 BCE, they marked the winter and summer solstices respectively. Furthermore, Hydra had been a landmark as it had straddled the equator in antiquity. Corvus and Crater also featured in the iconography of Mithraism, which is thought to have been of middle-eastern origin before spreading into Ancient Greece, according to the myth, Apollo saw through the fraud, and angrily cast the crow, cup, and snake, into the sky. In Chinese astronomy, the stars of Crater are located within the constellation of the Vermillion Bird of the South and they depict, along with some stars from Hydra, Yi, the Red Birds wings. Yi also denotes the 27th lunar mansion, alternatively, Yi depicts a heroic bowman, his bow composed of other stars in Hydra. In the Society Islands, Crater was recognized as a constellation called Moana-ohu-noa-ei-haa-moe-hara, covering 282.4 square degrees and hence 0. 685% of the sky, Crater ranks 53rd of the 88 constellations in area. It is bordered by Leo and Virgo to the north, Corvus to the east, Hydra to the south and west, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Crt. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of six segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 10h 51m 14s and 11h 56m 24s, while the coordinates are between −6. 66° and −25. 20°. Its position in the Southern Celestial Hemisphere means that the constellation is visible to observers south of 65°N. The German cartographer Johann Bayer used the Greek letters Alpha through Lambda to label the most prominent stars in the constellation, bode added more, though only Psi Crateris remains in use. John Flamsteed gave 31 stars in Crater and the segment of Hydra immediately below Crater Flamsteed designations, most of these stars lie in Hydra. Within the constellations borders, there are 33 stars brighter than or equal to apparent magnitude 6.5, the three brightest stars—Delta, Alpha and Gamma Crateris—from a triangle nearby the brighter star Nu Hydrae in neighbouring Hydra. Delta Crateris is the brightest star in Crater at magnitude 3.6 and it is an orange giant star of spectral type K0III that is 1. 0–1.4 times as massive as the Sun
Crater (constellation)
–
The constellation Crater as it can be seen by the naked eye.
Crater (constellation)
–
List of stars in Crater
Crater (constellation)
–
Corvus, Crater and other constellations seen around Hydra. From Urania's Mirror (1825)
71.
Crux
–
Crux /ˈkrʌks/ is a constellation located in the southern sky in a bright portion of the Milky Way. Its name is Latin for cross, and it is dominated by a cross-shaped or kite-like asterism that is known as the Southern Cross. The constellation contains four Cepheid variables that are visible to the eye under optimum conditions. Crux also contains the bright and colourful open cluster known as the Jewel Box and, to the southwest, partly includes the dark nebula. Crux was known to the Ancient Greeks due to the fact that it can be seen from southern Egypt and it was entirely visible as far north as Britain in the fourth millennium BC. However, the precession of the equinoxes gradually lowered its stars below the European horizon, by AD400, most of the constellation never rose above the horizon for Athenians. The 15th-century Venetian navigator Alvise Cadamosto made note of what was probably the Southern Cross on exiting the Gambia River in 1455, however, Cadamostos accompanying diagram was inaccurate. Faras sketched and described the constellation in a letter written on the beaches of Brazil on May 1,1500, explorer Amerigo Vespucci seems to have observed not only the Southern Cross but also the neighboring Coalsack Nebula on his second voyage in 1501–02. Both authors, however, depended on unreliable sources and placed Crux in the wrong position, Crux was first shown in its correct position on the celestial globes of Petrus Plancius and Jodocus Hondius in 1598 and 1600. Its stars were first catalogued separately from Centaurus by Frederick de Houtman in 1603, later adopters of the constellation included Jakob Bartsch in 1624 and Augustin Royer in 1679. Royer is sometimes cited as initially distinguishing Crux. Crux is bordered by the constellations Centaurus on the east, north and west, covering 68 square degrees and 0. 165% of the night sky, it is the smallest of the 88 constellations. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Cru, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of four segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 11h 56. 13m and 12h 57. 45m, while the coordinates are between −55. 68° and −64. 70°. The whole constellation is visible to observers south of latitude 25°N, in tropical regions Crux can be seen in the sky from April to June. Crux is exactly opposite to Cassiopeia on the sphere. For locations south of 34°S, Crux is circumpolar and thus visible in the night sky. Crux is sometimes confused with the nearby False Cross by stargazers, Crux is somewhat kite-shaped, and it has a fifth star
Crux
–
The five brightest stars in Crux are clearly visible in the top right. The red giant Gacrux and orange giant Epsilon are distinctly different from the three other major stars of the constellation, which are blue-white in colour.
Crux
–
List of stars in Crux
Crux
–
Deep exposure of Crux, Coalsack Nebula, and IC 2944
Crux
–
Stacked image of six identical frames of Crux.
72.
Delphinus
–
Delphinus /dɛlˈfaɪnəs/ is a constellation in the northern sky, close to the celestial equator. Its name is Latin for dolphin, Delphinus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains among the 88 modern constellations recognized by the International Astronomical Union. It is one of the constellations, ranked 69th in size. Delphinus brightest stars form an asterism that can easily be recognized. It is bordered by Vulpecula the fox, Sagitta the arrow, Aquila the eagle, Aquarius the water-carrier, Equuleus the foal, Delphinus does not have any bright stars, its brightest star is of magnitude 3.8. The main asterism in Delphinus is Jobs Coffin, formed from the four brightest stars, Alpha, Beta, Gamma, Alpha and Beta Delphini are named Sualocin and Rotanev, respectively. When read backwards, they read as Nicolaus Venator, the Latinized name of Palermo Observatorys former director, however, Delphinus is in a rich Milky Way star field. Alpha Delphini, called Sualocin, is a blue-white hued main sequence star of magnitude 3.8,241 light-years from Earth, Beta Delphini, called Rotanev, is a close binary star and the brightest in Delphinus, divisible in only large amateur telescopes. To the unaided eye, it appears to be a star of magnitude 3.6. It has a period of 27 years and is 97 light-years from Earth, Gamma Delphini is a celebrated binary star among amateur astronomers. The primary is a star of magnitude 4.3. 102 light-years away, the components of Gamma Delphini are divisible in an amateur telescope. The secondary, also described as green, is 10 arcseconds from the primary, struve 2725, called the Ghost Double, is a pair that appears similar to a dimmer Gamma Delphini. Its components of magnitudes 7.6 and 8.4 are separated by 6 arcseconds and are 15 arcminutes from Gamma Delphini itself, there are several dimmer stars in Delphinus. Delta Delphini is a type A7 IIIp star of magnitude 4.43, epsilon Delphini, called Deneb Dulfim, meaning tail of the Dolphin, is a star of spectral class B6 III and magnitude 4. Delphinus is also home to several variable stars, R Delphini is a Mira-type variable star with a period of 285.5 days. Its magnitude ranges between a maximum of 7.6 and a minimum of 13.8, rho Aquilae moved across the border into Delphinus in 1992. HR Delphini was a nova that brightened to magnitude 3.5 in December 1967, on 14 August 2013, a possible nova was discovered by amateur astronomer Koichi Itagaki, initially labelled PNV J20233073+2046041, now labelled Nova Delphini 2013
Delphinus
–
The constellation Delphinus as it can be seen by the naked eye.
Delphinus
–
List of stars in Delphinus
Delphinus
–
Delphinus is depicted on the left of this card from Urania's Mirror (1825)
73.
Dorado
–
Dorado is a constellation in the southern sky. It was named in the late 16th century and is now one of the 88 modern constellations and its name refers to the dolphinfish, which is known as dorado in Portuguese, although it has also been depicted as a swordfish. Dorado contains most of the Large Magellanic Cloud, the remainder being in the constellation Mensa, the South Ecliptic pole also lies within this constellation. Its first depiction in an atlas was in Johann Bayers Uranometria of 1603 where it was also named Dorado. Dorado has been represented historically as a dolphinfish and a swordfish and it has also been represented as a goldfish. The constellation was known in the 17th and 18th century as Xiphias. The name Dorado ultimately become dominant and was adopted by the IAU, alpha Doradus is a blue-white star of magnitude 3.3,176 light-years from Earth. It is the brightest star in Dorado, Beta Doradus is a notably bright Cepheid variable star. It is a supergiant star that has a minimum magnitude of 4.1. One thousand and forty light-years from Earth, Beta Doradus has a period of 9 days and 20 hours, R Doradus is one of the many variable stars in Dorado. S Dor,9.721 hypergiant in the Large Magellanic Cloud, is the prototype of S Doradus variable stars, the variable star R Doradus 5.73 has the largest known apparent size of any star other than the Sun. Gamma Doradus is the prototype of the Gamma Doradus variable stars, supernova 1987A was the closest supernova to occur since the invention of the telescope. SNR 0509-67.5 is the remnant of an unusually energetic Type 1a supernova from about 400 years ago, HE 0437-5439 is a hypervelocity star escaping from the Milky Way/Magellanic Cloud system. Dorado is also the location of the South Ecliptic pole, which lies near the fishs head, the pole was called Polus Doradinalis by Willem Jansson Blaeu. Because Dorado contains part of the Large Magellanic Cloud, it is rich in deep sky objects, the Large Magellanic Cloud,1,000 light-years in diameter, is a satellite galaxy of the Milky Way Galaxy, located at a distance of 179,000 light-years. It has been deformed by its interactions with the larger Milky Way. In 1987, it became host to SN 1987A, the first supernova of 1987 and this 25, 000-light-year-wide galaxy contains over 10,000 million stars. All coordinates given are for Epoch J2000.0, NGC1566 is a face-on spiral galaxy
Dorado
–
The constellation Dorado as it can be seen by the naked eye.
Dorado
–
List of stars in Dorado
Dorado
–
NGC 1566 is an intermediate spiral galaxy.
Dorado
–
LEDA 89996 is a classic example of a spiral galaxy.
74.
Grus (constellation)
–
Grus is a constellation in the southern sky. Its name is Latin for the crane, a type of bird and it is one of twelve constellations conceived by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Grus first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayers star atlas Uranometria of 1603, the constellations Grus, Pavo, Phoenix and Tucana are collectively known as the Southern Birds. The constellations brightest star, Alpha Gruis, is known as Alnair. Beta Gruis is a red giant variable star with a magnitude of 2.3. Six star systems have found to have planets, the red dwarf Gliese 832 is one of the closest stars to Earth to have a planetary system. Another—WASP-95—has a planet that orbits every two days, deep-sky objects found in Grus include the planetary nebula IC5148, also known as the Spare Tyre Nebula, and a group of four interacting galaxies known as the Grus Quartet. The stars that form Grus were originally considered part of the neighbouring constellation Piscis Austrinus, Grus first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius. Its first depiction in an atlas was in the German cartographer Johann Bayers Uranometria of 1603. De Houtman included it in his star catalogue the same year under the Dutch name Den Reygher, The Heron. Astronomer Ian Ridpath has reported the symbolism likely came from Plancius originally, Grus and the nearby constellations Phoenix, Tucana and Pavo are collectively called the Southern Birds. The stars that correspond to Grus were generally too far south to be seen from China, in Chinese astronomy, Gamma and Lambda Gruis may have been included in the tub-shaped asterism Bàijiù, along with stars from Piscis Austrinus. Alpha and Beta Gruis, along with Fomalhaut, Alpha Pavonis, Grus is bordered by Piscis Austrinus to the north, Sculptor to the northeast, Phoenix to the east, Tucana to the south, Indus to the southwest, and Microscopium to the west. Bayer straightened the tail of Piscis Austrinus to make way for Grus in his Uranometria, covering 366 square degrees, it ranks 45th of the 88 modern constellations in size and covers 0. 887% of the night sky. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Gru, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined as a polygon of 6 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 21h 27. 4m and 23h 27. 1m, while the coordinates are between −36. 31° and −56. 39°. Keyser and de Houtman assigned twelve stars to the constellation, Bayer depicted Grus on his chart, but did not assign its stars Bayer designations. French explorer and astronomer Nicolas Louis de Lacaille labelled them Alpha to Phi in 1756 with some omissions, in 1879, American astronomer Benjamin Gould added Kappa, Nu, Omicron and Xi, which had all been catalogued by Lacaille but not given Bayer designations
Grus (constellation)
–
The constellations Grus and Piscis Austrinus, which once formed a single constellation, as depicted in Atlas Coelestis by Johann Doppelmayr, ca. 1742
Grus (constellation)
–
List of stars in Grus
Grus (constellation)
–
The "southern birds", as depicted in Johann Bayer 's Uranometria
Grus (constellation)
–
The constellation Grus as it can be seen by the naked eye
75.
Hercules (constellation)
–
Hercules is a constellation named after Hercules, the Greek mythological hero adapted from the Greek hero Heracles. Hercules was one of the 48 constellations listed by the 2nd century astronomer Ptolemy and it is the fifth largest of the modern constellations. Hercules is bordered by Draco to the north, Boötes, Corona Borealis, and Serpens Caput to the east, Ophiuchus to the south, Aquila to the southwest, and Sagitta, Vulpecula, and Lyra to the west. Covering 1225.1 square degrees and 2. 970% of the night sky, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Her. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 32 segments, in mid-northern latitudes, Hercules is best observed from mid-Spring until the early part of the Fall season, culminating at midnight on June 13. The solar apex is the direction of the Suns motion with respect to the Local Standard of Rest and this is located within the constellation of Hercules, around coordinates Right Ascension 18h 00m and Declination 30°. The north pole of the coordinate system is located within this constellation at Right Ascension 18h 55m 01s. Hercules has no first or second magnitude stars, however, it does have several stars above magnitude 4. Alpha Herculis, traditionally called Rasalgethi, is a star system. The primary is a variable star, it is a bright giant with a minimum magnitude of 4. It has a diameter of roughly 400 solar diameters, the secondary, a spectroscopic binary that orbits the primary every 3600 years, is a blue-green hued star of magnitude 5.6. Its common name means the kneelers head, Beta Herculis, also called Kornephoros, is the brightest star in Hercules. It is a giant of magnitude 2.8,148 light-years from Earth. Deltoide 5512 is a double star divisible in amateur telescopes. The primary is a star of magnitude 3.1. The optical companion is of magnitude 8.2, gamma Herculis is also a double star divisible in small amateur telescopes. The primary is a giant of magnitude 3.8,195 light-years from Earth. The optical companion, widely separated, is 10th magnitude, zeta Herculis is a binary star that is becoming divisible in medium-aperture amateur telescopes, as the components widen to their peak in 2025
Hercules (constellation)
–
The constellation Hercules as it can be seen by the naked eye.
Hercules (constellation)
–
List of stars in Hercules
Hercules (constellation)
–
Hercules as depicted in Urania's Mirror, a set of constellation cards published in London c.1825. The figure appears upside down in the sky relative to neighbouring constellations.
76.
Horologium (constellation)
–
Horologium is a faint constellation in the southern sky. It was devised by French astronomer Nicolas Louis de Lacaille in 1752, the constellations brightest star is Alpha Horologii, an orange giant. R Horologii is a red giant Mira variable with one of the widest ranges in brightness known, three star systems have exoplanets, while Nu Horologii has a debris disk. He devised fourteen new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe, all but one honoured instruments that symbolised the Age of Enlightenment. Lacaille Latinised the name to Horologium on his 1763 chart, covering a total of 248.9 square degrees or 0. 603% of the sky, Horologium ranks 58th in area out of the 88 modern constellations. Its position in the Southern Celestial Hemisphere means that the constellation is visible to observers south of 23°N. Horologium is bordered by five different constellations, Eridanus, Caelum, Reticulum, Dorado, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Hor. The official constellation boundaries are defined by a twenty-two sided polygon, in the equatorial coordinate system, the right ascension coordinates of these borders lie between 02h 12. 5m and 04h 20. 2m, while the declination coordinates are between −39. 63° and −67. 04°. Horologium has only one star brighter than apparent magnitude 4, and 41 stars brighter than or equal to magnitude 6.5, Lacaille charted and designated 11 stars with the Bayer designations Alpha through to Lambda Horologii in 1756. Baily removed the designations of Epsilon and Theta Horologii as he held they were too faint to warrant naming and he was unable to find a star that corresponded to the coordinates Lacailles Beta Horologii. Determining that the coordinates were wrong, he assigned the designation to another star, kappa Horologii, too, was unable to be verified, yet was most likely the star HD18292. Gould assigned designations to what became Mu and Nu Horologii as he felt they were enough to warrant them. Alpha Horologii, the brightest, is a giant of magnitude 3.9. Bode depicted it as the pendulum, while Lacaille made it one of the weights. Beta Horologii is a giant of magnitude 5.0,314 light-years from Earth. Lambda Horologii is an ageing giant star of spectral type F2III that spins around at 140 km/second. It is 161 ±1 light-years from Earth, however, Horologium does have several variable stars. R Horologii is a red giant Mira variable with one of the widest ranges in brightness known and it has a minimum magnitude of 14.3 and a maximum magnitude of 4.7, its period is approximately 13 months
Horologium (constellation)
–
The constellation Horologium as it can be seen by the naked eye.
Horologium (constellation)
–
List of stars in Horologium
77.
Lacerta
–
Lacerta is one of the 88 modern constellations defined by the International Astronomical Union. Its name is Latin for lizard, a small, faint constellation, it was created in 1687 by the astronomer Johannes Hevelius. Its brightest stars form a W shape similar to that of Cassiopeia and it is located between Cygnus, Cassiopeia and Andromeda on the northern celestial sphere. The northern part lies on the Milky Way and it also contains the prototypic blazar BL Lacertae. Alpha Lacertae is a blue-white hued main-sequence star of magnitude 3.8,102 light-years from Earth and it has a spectral type of A1 V and is an optical double star. Beta Lacertae is far dimmer, a giant of magnitude 4.4,170 light-years from Earth. Roe 47 is a star consisting of five components. ADS16402 is a star system in Lacerta, around which a planet orbits with some unusual properties. The Jupiter-sized planet exhibits a low density, about the same as cork. This planet is dubbed HAT P-1, EV Lacertae is a rapidly spinning magnitude 10 red dwarf with a strong magnetic field. It is a star that can emit powerful flares potentially visible to the naked eye. NGC7243 is an open cluster 2500 light-years from Earth, visible in amateur telescopes. It has a few dozen scattered stars, the brightest of which are of the 8th magnitude, BL Lacertae is the prototype of the BL Lacertae objects, which appear to be dim variable stars but are actually the variable nuclei of elliptical galaxies, they are similar to quasars. It lent its name to a type of celestial objects. The object varies irregularly between magnitudes 14 and 17 over a few days, centred on a region of the sky without apparently bright stars, Lacerta was apparently not regarded as a constellation by ancient Western astronomers. Johannes Hevelius created the constellation in 1687 and initially christened it Stellio, both Sceptrum and Frederici Honores are now obsolete, while Lacerta still survives. Similarly, the Chumash people of California call this part of the sky Lizard, USS Lacerta was an attack cargo ship in the United States navy named after the constellation. Ridpath, Ian, Tirion, Wil, Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2 Ian Ridpath, Stars and Planets Guide, Collins, London
Lacerta
–
The constellation Lacerta as it can be seen by the naked eye.
Lacerta
–
List of stars in Lacerta
Lacerta
–
Lacerta can be seen on the left of this 1825 star map from Urania's Mirror
78.
Leo Minor
–
Leo Minor is a small and faint constellation in the northern celestial hemisphere. Its name is Latin for the lion, in contrast to Leo. It lies between the larger and more recognizable Ursa Major to the north and Leo to the south, Leo Minor was not regarded as a separate constellation by classical astronomers, it was designated by Johannes Hevelius in 1687. There are 37 stars brighter than apparent magnitude 6.5 in the constellation,46 Leonis Minoris, an orange giant of magnitude 3.8, is located some 95 light-years from Earth. At magnitude 4.4, Beta Leonis Minoris is the second-brightest star and it is a binary star, the brighter component of which is an orange giant and the fainter a yellow-white main sequence star. The third-brightest star is 21 Leonis Minoris, a rapidly rotating white main-sequence star of average magnitude 4.5, the constellation also includes two stars with planetary systems, two pairs of interacting galaxies, and the unique deep-sky object Hannys Voorwerp. Hevelius decided upon Leo Minor or Leo Junior as a depiction that would align with its neighbours the Lion. In 1845, English astronomer Francis Baily revised the catalogue of Heveliuss new constellations, proctor gave the constellation the name Leaena the Lioness in 1870, explaining that he sought to shorten the constellation names to make them more manageable on celestial charts. Arabist Friedrich Wilhelm Lach describes a different view, noting that they had seen as Al Haud the Pond. A line of four stars was known as Shaowei, it represented four Imperial advisors and may have located in Leo Minor. It is a constellation bordered by Ursa Major to the north, Lynx to the west, Leo to the south. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is LMi, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 16 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 9h 22. 4m and 11h 06. 5m, while the coordinates are between 22. 84° and 41. 43°. Ranked 64th out of 88 constellations in size, Leo Minor covers an area of 232.0 square degrees and it culminates each year at midnight on February 24, and at 9 p. m. on May 24. There are only three stars in the constellation brighter than magnitude 4.5, and 37 stars with a magnitude brighter than 6.5, Leo Minor does not have a star designated Alpha because Baily erred and allocated a Greek letter to only one star, Beta. It is unclear whether he intended to give 46 Leonis Minoris a Bayer designation and he died before revising his proofs, which might explain this stars omission. At magnitude 3.8, the brightest star in Leo Minor is a giant of spectral class K0III named 46 Leonis Minoris or Praecipua. Situated 95 light-years from Earth, it has around 32 times the luminosity and is 8.5 times the size of the Sun and it was also catalogued and named as o Leonis Minoris by Johann Elert Bode, which has been misinterpreted as Omicron Leonis Minoris
Leo Minor
–
Leo Minor as seen by the naked eye
Leo Minor
–
List of stars in Leo Minor
Leo Minor
–
Leo Minor above the head of Leo, as depicted in Urania's Mirror, a set of constellation cards published in London c. 1825
Leo Minor
–
Spiral galaxy NGC 3021 which lies about 100 million light-years away.
79.
Lepus (constellation)
–
Lepus is a constellation lying just south of the celestial equator, immediately south of Orion. Its name is Latin for hare and it is located below the constellation Orion, and is sometimes represented as a hare being chased by Orion or, alternatively, by Orions hunting dogs. This constellation should not be confused with Lupus, the wolf, Lepus is most often represented as a rabbit being hunted by Orion, whose hunting dogs pursue it. The constellation is also associated with some lunar mythology, including the Moon rabbit, there are a fair number of bright stars, both single and double, in Lepus. Alpha Leporis, the brightest star of Lepus, is a supergiant of magnitude 2.6,1300 light-years from Earth. Its traditional name, Arneb, means hare, beta Leporis, called Nihal, is a yellow giant of magnitude 2.8,159 light-years from Earth. Gamma Leporis is a double star divisible in binoculars, the primary is a yellow star of magnitude 3.6,29 light-years from Earth. The secondary is a star of magnitude 6.2. Delta Leporis is a giant of magnitude 3.8,112 light-years from Earth. Epsilon Leporis is a giant of magnitude 3.2,227 light-years from Earth. Kappa Leporis is a double star divisible in medium amateur telescopes,560 light-years from Earth. The primary is a star of magnitude 4.4. There are several stars in Lepus. R Leporis is a Mira variable star also called Hinds Crimson Star for its red color. It varies in magnitude from a minimum of 9.8 to a maximum of 7.3, R Leporis is at a distance of 1500 light-years. The color intensifies as the star brightens and it can be as dim as magnitude 12 and as bright as magnitude 5.5. It was named for John Russell Hind, T Leporis is also a Mira variable observed in detail by ESOs Very Large Telescope Interferometer. RX Leporis is a red giant that has a period of 2 months
Lepus (constellation)
–
Lepus as seen in Urania's Mirror (1825)
Lepus (constellation)
–
List of stars in Lepus
Lepus (constellation)
–
The constellation Lepus as it can be seen by the naked eye.
80.
Lupus (constellation)
–
Lupus /ˈljuːpəs/ is a constellation located in the deep southern sky. Its name is Latin for wolf, in ancient times, the constellation was considered an asterism within Centaurus, and was considered to have been an arbitrary animal, killed, or about to be killed, on behalf of, or for, Centaurus. An alternative visualization, attested by Eratosthenes, saw this constellation as a held by Centaurus. It was not separated from Centaurus until Hipparchus of Bithynia named it Therion in the 3rd century BC, no particular animal was associated with it until the Latin translation of Ptolemys work identified it with the wolf. The Greek constellation is based on the Babylonian figure known as the Mad Dog. This was a hybrid creature that combined the head and torso of a man with the legs. It is often found in association with the sun god and another mythical being called the Bison-man, Lupus is bordered by six different constellations, although one of them merely touches at the corner. The other five are Scorpius, Norma, Circinus, Libra, covering 333.7 square degrees and 0. 809% of the night sky, it ranks 46th of the 88 modern constellations. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Lup, the official constellation boundaries are defined by a twelve-sided polygon. The whole constellation is visible to observers south of latitude 34°N, overall, there are 127 stars within the constellations borders brighter than or equal to apparent magnitude 6.5. In his book Star Names and Their Meanings, R. H. Allen gave the names Yang Mun for Alpha Lupi, the brightest star in Lupus, and KeKwan for the blue giant Beta Lupi, both from Chinese. However, the first name is in error, both stars were part of a large Chinese constellation known in modern transliteration as Qíguān, the Imperial Guards, most of the brightest stars in Lupus are massive members of the nearest OB association, Scorpius-Centaurus. Alpha Lupi is a blue giant star of spectral type B1.5 III that is 460 ±10 light-years distant from Earth. It is a Beta Cephei variable, pulsating in brightness by 0.03 of a magnitude every 7 hours and 6 minutes, towards the north of the constellation are globular clusters NGC5824 and NGC5986, and close by the dark nebula B228. To the south are two clusters, NGC5822 and NGC5749, as well as globular cluster NGC5927 on the eastern border with Norma. On the western border are two spiral galaxies and the Wolf-Rayet planetary nebula IC4406, containing some of the hottest stars in existence, IC4406, also called the Retina Nebula, is a cylindrical nebula at a distance of 5,000 light-years. It has dust lanes throughout its center, another planetary nebula, NGC5882, is towards the center of the constellation. The transiting exoplanet Lupus-TR-3b lies in this constellation, the historic supernova SN1006 is described by various sources as appearing on April 30 to May 1,1006, in the constellation of Lupus
Lupus (constellation)
–
Lupus is located in the bottom-left corner of card 32 in Urania's Mirror (1825)
Lupus (constellation)
–
List of stars in Lupus
Lupus (constellation)
–
The constellation Lupus as it can be seen by the naked eye.
Lupus (constellation)
–
Planetary nebula NGC 5882. (Credit: HST/ NASA / ESA).
81.
Lynx (constellation)
–
Lynx, named after the animal, is a constellation in the northern sky that was introduced in the 17th century by Johannes Hevelius. It is a faint constellation with its brightest stars forming a zigzag line, the orange giant Alpha Lyncis is the brightest star in the constellation, while the semiregular variable star Y Lyncis is a target for amateur astronomers. Six star systems have found to contain planets. Those of 6 Lyncis and HD75898 were discovered by the Doppler method, polish astronomer Johannes Hevelius formed the constellation in the 17th century from 19 faint stars that he observed with the unaided eye between the constellations Ursa Major and Auriga. Naming it Lynx because of its faintness, he challenged future stargazers to see it, Hevelius gave it the alternate name of Tiger in his catalogue as well, but kept the former name only in his atlas. English astronomer John Flamsteed adopted the constellation in his catalogue, published in 1712, Lynx is bordered by Camelopardalis to the north, Auriga to the west, Gemini to the southwest, Cancer to the south, Leo to the east and Ursa Major to the northeast. Covering 545.4 square degrees and 1. 322% of the sky, it ranks 28th of the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Lyn, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 20 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 06h 16m 13. 76s and 09h 42m 50. 22s, while the coordinates are between +32. 97° and +61. 96°. On dark nights, the stars can be seen as a crooked line extending roughly between Camelopardalis and Leo, and north of the bright star Castor. Lynx is most readily observed from the winter to late summer to northern hemisphere observers. The whole constellation is visible to observers north of latitude 28°S, english astronomer Francis Baily gave a single star a Bayer designation—Alpha Lyncis—while Flamsteed numbered 44 stars, though several lie across the boundary in Ursa Major. Overall, there are 97 stars within the constellations borders brighter than or equal to apparent magnitude 6.5, the brightest star in this constellation is Alpha Lyncis, with an apparent magnitude of 3.14. It is a giant of spectral type K7III located 203 ±2 light-years distant from Earth. Around twice as massive as the Sun, it has exhausted the hydrogen at its core and has evolved away from the main sequence, the star has swollen to about 55 times the Suns radius and it is emitting roughly 673 times the luminosity of the Sun. The stellar atmosphere has cooled, giving it a surface temperature of 3,880 K, the only star with a proper name is Alsciaukat, also known as 31 Lyncis, located 380 ±10 light-years from Earth. This star is also a giant with around twice the Suns mass that has swollen. It is anywhere from 59 to 75 times as wide as the Sun, Alsciaukat is also a variable star, ranging in brightness by 0.05 magnitude over 25 to 30 days from its baseline magnitude of 4.25
Lynx (constellation)
–
Illustration from Urania's Mirror (1825). The obsolete constellation Telescopium Herschelii is to its right.
Lynx (constellation)
–
List of stars in Lynx
82.
Mensa (constellation)
–
Mensa is a small constellation in the Southern Celestial Hemisphere between Scorpius and Centaurus, one of twelve drawn up in the 18th century by French astronomer Nicolas Louis de Lacaille. Its name is Latin for table, though it originally depicted Table Mountain and was known as Mons Mensae. One of the 88 modern constellations, it covers a keystone-shaped wedge of sky stretching from approximately 4h to 7. 5h of right ascension, other than the south polar constellation of Octans, it is the most southerly of constellations. As a result, it is essentially unobservable from the Northern Hemisphere, one of the faintest constellations in the night sky, Mensa boasts no bright stars. Its brightest star, Alpha Mensae is barely visible in suburban skies, two star systems in Mensa have been found to have planets, and part of the Large Magellanic Cloud lies within the constellations borders. Initially known as Mons Mensae, Mensa was created by Nicolas Louis de Lacaille out of dim Southern Hemisphere stars in honor of Table Mountain, a South African mountain overlooking Cape Town. He recalled that the Magellanic clouds were sometimes known as Cape clouds, hence he made a table in the sky under the clouds. Lacaille had observed and catalogued 10,000 southern stars during a stay at the Cape of Good Hope. He devised 14 new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe, Mensa was the only constellation that did not honor an instrument that symbolised the Age of Enlightenment. John Herschel proposed shrinking the name to one word in 1844, although the stars of Mensa do not feature in any ancient mythology, the mountain it is named after has a rich mythology. Called Tafelberg in Dutch and German, the mesa has two neighboring mountains called Devils Peak and Lions Head, Table Mountain features in the mythology of the Cape of Good Hope, notorious for its storms—the explorer Bartolomeu Dias saw the mesa as a mythical anvil for storms. Another myth relating to its dangers comes from Sinbad the Sailor, Mensa is bordered by Dorado to the north, Hydrus to the northwest and west, Octans to the south, Chamaeleon to the east and Volans to the northeast. Covering 153.5 square degrees and 0. 372% of the night sky, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Men. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of eight segments, the whole constellation is visible to observers south of latitude 5°N. Lacaille labelled eleven stars with Bayer designations Alpha through to Lambda, Gould later added Kappa, Mu, Nu, Xi and Pi Mensae. Stars as dim as these were not generally given designations, however, overall, there are 22 stars within the constellations borders brighter than or equal to apparent magnitude 6.5. Mensa contains no stars, with Alpha Mensae its brightest star with a barely visible apparent magnitude of 5.09. Alpha Mensae is a solar-type star 33.26 ±0.05 light-years from Earth, an infrared excess has been detected around this star, most likely indicating the presence of a circumstellar disk at a radius of over 147 AU
Mensa (constellation)
–
The constellation Mensa as it can be seen by the naked eye.
Mensa (constellation)
–
List of stars in Mensa
83.
Microscopium
–
Its name is a Latinised form of the Greek word for microscope. Its stars are faint and hardly visible from most of the non-tropical Northern Hemisphere, the constellations brightest star is Gamma Microscopii of apparent magnitude 4.68, a yellow giant 2.5 times the Suns mass located around 381 light-years distant. It passed within 1.14 and 3.45 light-years of the Sun some 3.9 million years ago, two star systems—WASP-7 and HD 205739—have planets, while two others—the young red dwarf star AU Microscopii and the sunlike HD 202628—have debris disks. AU Microscopii and the red dwarf system AT Microscopii are probably a wide triple system. Nicknamed Speedy Mic, BO Microscopii is a star with an extremely fast rotation period of 9 hours 7 minutes, the recommended three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Mic. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of four segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 20h 27. 3m and 21h 28. 4m, while the coordinates are between −27. 45° and −45. 09°. The whole constellation is visible to observers south of latitude 45°N, given that its brightest stars are of fifth magnitude, the constellation is invisible to the naked eye in areas with polluted skies. French astronomer Nicolas Louis de Lacaille charted and designated ten stars with the Bayer designations Alpha through to Iota in 1756, a star in neighbouring Indus that Lacaille had labelled Nu Indi turned out to be in Microscopium, so Gould renamed it Nu Microscopii. Francis Baily considered Gamma and Epsilon Microscopii to belong to the neighbouring constellation Piscis Austrinus, in his 1725 Catalogus Britannicus, John Flamsteed labelled the stars 1,2,3 and 4 Piscis Austrini, which became Gamma Microscopii, HR8076, HR8110 and Epsilon Microscopii respectively. Within the constellations borders, there are 43 stars brighter than or equal to apparent magnitude 6.5, depicting the eyepiece of the microscope is Gamma Microscopii, which—at magnitude of 4. 68—is the brightest star in the constellation. Measurement of its parallax yields a distance of 229±4 light years from Earth. At around 2.5 times the mass of the Sun, it passed within 1.14 and 3.45 light-years of the Sun some 3.9 million years ago, possibly massive enough. Alpha Microscopii is also a yellow giant star of spectral type G7III with an apparent magnitude of 4.90. Located 380±30 light-years away from Earth, it has swollen to 17.5 times the diameter of the Sun, Alpha has a 10th magnitude companion, visible in 7.5 cm telescopes, though this is a coincidental closeness rather than a true binary system. Epsilon Microscopii lies 182±2 light years away, and is a star of apparent magnitude 4.7. Theta1 and Theta2 Microscopii make up a wide double whose components are splittable to the naked eye, both are white A-class magnetic spectrum variable stars with strong metallic lines, similar to Cor Caroli. They mark the constellations specimen slide, many notable objects are too faint to be seen with the naked eye
Microscopium
–
The constellation Microscopium as it can be seen by the naked eye.
Microscopium
–
List of stars in Microscopium
Microscopium
–
Seen in the 1824 star chart set Urania's Mirror (in the lower left)
84.
Monoceros
–
Monoceros is a faint constellation on the celestial equator. Its name is Greek for unicorn and its definition is attributed to the 17th-century Dutch cartographer Petrus Plancius. It is bordered by Orion to the west, Gemini to the north, Canis Major to the south, other bordering constellations include Canis Minor, Lepus and Puppis. Monoceros is not easily seen with the eye, containing only a few fourth magnitude stars. Alpha Monocerotis has a magnitude of 3.93, slightly brighter than Gamma Monocerotis at 3.98. Beta Monocerotis is a star system, the three stars forming a triangle which seems to be fixed. The visual magnitudes of the stars are 4.7,5.2 and 6.1, William Herschel discovered it in 1781 and commented that it is one of the most beautiful sights in the heavens. Epsilon Monocerotis is a binary, with visual magnitudes of 4.5 and 6.5. S Monocerotis, or 15 Monocerotis, is a bluish white variable star and is located at the center of NGC2264, the variation in its magnitude is slight. It has a star of visual magnitude 8. V838 Monocerotis, a red supergiant star, had an outburst starting on January 6,2002, in February of that year. After the outburst was over, the Hubble Space Telescope was able to observe a light echo, Monoceros also contains Plasketts Star, which is a massive binary system whose combined mass is estimated to be that of almost 100 Suns put together. Monoceros contains two super-Earth exoplanets in one system, COROT-7b was detected by the COROT satellite and COROT-7c was detected by HARPS from ground-based telescopes. Until the announcement of Kepler-10b in January 2011, COROT-7b was the smallest exoplanet to have its diameter measured, both planets in this system were discovered in 2009. Monoceros contains many clusters and nebulae, most notable among them, M50 and it has an overall magnitude of 6.0 and is 4900 light-years from Earth. The Rosette Nebula, over 100 light-years in diameter, has a star cluster. It was independently discovered in the 1880s by Lewis Swift and Edward Emerson Barnard as they hunted for comets, the Christmas Tree Cluster is another open cluster in Monoceros. Named for its resemblance to a Christmas tree, it is bright at an overall magnitude of 3.9
Monoceros
–
The constellation Monoceros as it can be seen by the naked eye.
Monoceros
–
List of stars in Monoceros
Monoceros
–
The constellation Monoceros, from Urania's Mirror, a set of star charts from 1825. Includes Canis Minor and the obsolete constellation Atelier Typographique
85.
Perseus (constellation)
–
Perseus is a constellation in the northern sky, being named after the Greek mythological hero Perseus. It is one of the 48 listed by the 2nd-century astronomer Ptolemy and it is located near several other constellations named after ancient Greek legends surrounding Perseus, including Andromeda to the west and Cassiopeia to the north. Perseus is also bordered by Aries and Taurus to the south, Auriga to the east, Camelopardalis to the north, the galactic plane of the Milky Way passes through Perseus, whose brightest star is the yellow-white supergiant Alpha Persei, which shines at magnitude 1.79. It and many of the stars are members of an open cluster known as the Alpha Persei Cluster. The best-known star, however, is Algol, linked with ominous legends because of its variability, rather than being an intrinsically variable star, it is an eclipsing binary. Other notable star systems in Perseus include X Persei, a system containing a neutron star, and GK Persei. The Double Cluster, comprising two open clusters quite near each other in the sky, was known to the ancient Chinese, the constellation gives its name to the Perseus cluster, a massive galaxy cluster located 250 million light-years from Earth. It hosts the radiant of the annual Perseids meteor shower—one of the most prominent meteor showers in the sky, the constellation of Perseus may be derived from the Babylonian Old Man constellation, then associated with East in the MUL. APIN—an astronomical compilation dating to around 1000 BCE. In Greek mythology, Perseus was the son of Danaë, who was sent by King Polydectes to bring the head of Medusa the Gorgon—whose visage caused all who gazed upon her to turn to stone—as a wedding gift. Perseus slew Medusa in her sleep, and Pegasus and Chrysaor appeared from her body, Perseus continued to the realm of Cepheus whose daughter Andromeda was to be sacrificed to Cetus the sea monster. Perseus rescued Andromeda from the monster by killing it with his diamond sword and he turned Polydectes and his followers to stone with Medusas head and appointed Dictys the fisherman king. Perseus and Andromeda married and had six children, in the sky, Perseus lies near the constellations Andromeda, Cepheus, Cassiopeia, Cetus, and Pegasus. Four Chinese constellations are contained in the area of the sky identified with Perseus in the West, incorporating stars from the northern part of the constellation, it contained Mu, Delta, Psi, Alpha, Gamma and Eta Persei. Lambda and possibly Mu Persei lay within it, dàlíng, the Great Trench, was the fifth paranatellon of that house, representing the trenches where criminals executed en masse in August were interred. It was formed by Kappa, Omega, Rho,24,17 and 15 Persei, the pile of corpses prior to their interment was represented by Jīshī, the sixth paranatellon of the house. The Double Cluster, h and Chi Persei, had special significance in Chinese astronomy, known as Hsi and Ho, the two clusters represented two astronomers who failed to predict a total solar eclipse and were subsequently beheaded. In Polynesia, Perseus was not commonly recognized as a constellation, the only people that named it were those of the Society Islands. Algol may have been named Matohi by the Māori people, Matohi occasionally came into conflict with Tangaroa-whakapau over which of them should appear in the sky, the outcome affecting the tides
Perseus (constellation)
–
Perseus carrying the head of Medusa the Gorgon, as depicted in Urania's Mirror, a set of constellation cards published in London c.1825
Perseus (constellation)
–
List of stars in Perseus
Perseus (constellation)
–
The constellation Perseus as it can be seen by the naked eye
Perseus (constellation)
–
The Double Cluster (NGC 869 and NGC 884)
86.
Phoenix (constellation)
–
Phoenix is a minor constellation in the southern sky. Named after the phoenix, it was first depicted on a celestial atlas by Johann Bayer in his 1603 Uranometria. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars, the constellation stretches from roughly −39° to −57° declination, and from 23. 5h to 2. 5h of right ascension. The constellations Phoenix, Grus, Pavo and Tucana, are known as the Southern Birds, the brightest star, Alpha Phoenicis, is named Ankaa, an Arabic word meaning the Phoenix. It is a giant of apparent magnitude 2.4. Next is Beta Phoenicis, actually a system composed of two yellow giants with a combined apparent magnitude of 3.3. Phoenix is the radiant of two meteor showers, the Phoenicids in December, and the July Phoenicids. Phoenix was the largest of the twelve constellations established by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and it first appeared on a 35-cm diameter celestial globe published in 1597 in Amsterdam by Plancius with Jodocus Hondius. The first depiction of this constellation in an atlas was in Johann Bayers Uranometria of 1603. De Houtman included it in his star catalog the same year under the Dutch name Den voghel Fenicx, The Bird Phoenix. One name of the brightest star Alpha Phoenicis—Ankaa—is derived from the Arabic العنقاء al-‘anqā’ the phoenix, in addition, the same group of stars was sometimes imagined by the Arabs as a boat, Al Zaurak, on the nearby river Eridanus. He observed, the introduction of a Phoenix into modern astronomy was, in a measure, the Chinese incorporated Phoenixs brightest star, Ankaa, and stars from the adjacent constellation Sculptor to depict Bakui, a net for catching birds. Phoenix and the constellation of Grus together were seen by Julius Schiller as portraying Aaron the High Priest. These two constellations, along with nearby Pavo and Tucana, are called the Southern Birds, the bright star Achernar is nearby. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Phe, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 10 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 23h 26. 5m and 02h 25. 0m, while the coordinates are between −39. 31° and −57. 84°. This means it remains below the horizon to anyone living north of the 40th parallel in the Northern Hemisphere and it is most visible from locations such as Australia and South Africa during late Southern Hemisphere spring. Most of the lies within, and can be located by, forming a triangle of the bright stars Achernar, Fomalhaut
Phoenix (constellation)
–
The constellation Phoenix as depicted in Johann Gabriel Doppelmayr 's Atlas Coelestis, ca. 1742.
Phoenix (constellation)
–
List of stars in Phoenix
Phoenix (constellation)
–
The "southern birds", as depicted in Johann Bayer 's Uranometria. Phoenix is on the lower left.
Phoenix (constellation)
–
The constellation Phoenix as it can be seen by the naked eye.
87.
Pictor
–
Pictor is a constellation in the Southern Celestial Hemisphere, located between the star Canopus and the Large Magellanic Cloud. Its name is Latin for painter, and is an abbreviation of the older name Equuleus Pictoris, normally represented as an easel, Pictor was named by Abbé Nicolas-Louis de Lacaille in the 18th century. The constellations brightest star is Alpha Pictoris, a white main-sequence star around 97 light-years away from Earth, Pictor also hosts RR Pictoris, a cataclysmic variable star system that flared up as a nova, reaching apparent magnitude 1.2 in 1925 before fading into obscurity. Another five stars in the constellation have been observed to have planets, among them is HD40307, an orange dwarf that has six planets orbiting it, one of which—HD40307 g—is a potential super-Earth in the circumstellar habitable zone. Kapteyns Star, the nearest star in Pictor to Earth, is a red dwarf located 12.76 light-years away that was found to have two super-Earths in orbit in 2014. Pictor A is a galaxy that is shooting an 800,000 light-year long jet of plasma from a supermassive black hole at its centre. In 2006, a gamma-ray burst—GRB 060729—was observed in Pictor, its extremely long X-ray afterglow detectable for two years. He devised 14 new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe, all but one honored instruments that symbolised the Age of Enlightenment. He gave these constellations Bayer designations, including ten stars in Pictor now named Alpha to Nu Pictoris. He labelled the constellation Equuleus Pictorius on his 1763 chart, the word Equuleus meaning small horse, the German astronomer Johann Bode called it Pluteum Pictoris. The name was shortened to its current form in 1845 by the English astronomer Francis Baily on the suggestion of his countryman Sir John Herschel. Pictor is a constellation bordered by Columba to the north, Puppis and Carina to the east, Caelum to the northwest, Dorado to the southwest. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Pic, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 18 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 04h 32. 5m and 06h 52. 0m, while the coordinates are between −42. 79° and −64. 15°. Pictor culminates each year at 9 p. m. on 17 March and its position in the far Southern Celestial Hemisphere means that the whole constellation is visible to observers south of latitude 26°N, and parts become circumpolar south of latitude 35°S. Pictor is a faint constellation, its three brightest stars can be seen near the prominent Canopus, within the constellations borders, there are 49 stars brighter than or equal to apparent magnitude 6.5. Located about 97 light-years away from Earth, Alpha Pictoris is the brightest star in the constellation, it is a white star with an apparent magnitude of 3.3. A rapidly spinning star with a rotational velocity estimated at 206 km/s
Pictor
–
Early depiction c.1756, when known as le Chevalet et la Palette; Canopus of Carina (the keel, or the hull, of the ship) seen at upper right
Pictor
–
List of stars in Pictor
Pictor
–
A photograph showing constellation Pictor as it can be seen by the naked eye (lines have been added that join up its three main stars). The bright star seen near Pictor is Canopus.
Pictor
–
Beta Pictoris Comparison.
88.
Piscis Austrinus
–
Piscis Austrinus is a constellation in the southern celestial hemisphere. The name is Latin for the fish, in contrast with the larger constellation Pisces. Prior to the 20th century, it was known as Piscis Notius. Its only star brighter than fourth magnitude is Fomalhaut, which is a star and is the eighteenth-brightest star in the night sky. Piscis Austrinus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, the stars of the modern constellation Grus once formed the tail of Piscis Austrinus. In 1597, Petrus Plancius carved out a separate constellation and named it after the crane, in Greek mythology, this constellation is known as the Great Fish and it is portrayed as swallowing the water being poured out by Aquarius, the water-bearer constellation. The two fish of the constellation Pisces are said to be the offspring of the Great Fish, in Egyptian mythology, this fish saved the life of the Egyptian goddess Isis, so she placed this fish and its descendants into the heavens as constellations of stars. Pisces Austrinus originated with the Babylonian constellation simply known as the Fish, professor of astronomy Bradley Schaefer has proposed that ancient observers must have been able to see as far south as Mu Piscis Austrini to define a pattern that looked like an fish. Piscis Austrinus is a constellation bordered by Capricornus to the northwest, Microscopium to the southwest, Grus to the south, Sculptor to the east, the recommended three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is PsA. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of four segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 21h 27. 3m and 23h 06. 5m, while the coordinates are between -24. 83° and -36. 46°. Fomalhaut traditionally represents the mouth of the fish, TW Piscis Austrini can be seen close by and is possibly associated with Fomalhaut as it lies within a light-year of it. Of magnitude 6.5, it is a BY Draconis variable, beta, Delta and Zeta constitute the Tien Kang in China. Beta is a star of apparent magnitude 4.29 and spectral type A0. Delta Piscis Austrini is a star with components of magnitude 4.2 and 9.2. Lacaille 9352 is a faint red dwarf star which is a mere 10.74 light-years away, at magnitude 7.34, it is too dim to be seen with the naked eye. NGC7172, NGC7174 and NGC7314 are three galaxies of magnitudes 11.9,12.5 and 10.9, respectively, stars and Planets Guide, Collins, London. The Deep Photographic Guide to the Constellations, Piscis Austrinus Star Tales – Piscis Austrinus Piscis Austrinus at Constellation Guide Warburg Institute Iconographic Database
Piscis Austrinus
–
Piscis Austrinus can be seen cut off at the bottom of Urania's Mirror ' s 1825 depiction of Aquarius. Next to it is the obsolete constellation Ballon Aerostatique.
Piscis Austrinus
–
List of stars in Piscis Austrinus
Piscis Austrinus
–
The constellation Piscis Austrinus as it can be seen by the naked eye.
89.
Pyxis
–
Pyxis is a small and faint constellation in the southern sky. Abbreviated from Pyxis Nautica, its name is Latin for a mariners compass, Pyxis was introduced by Nicolas Louis de Lacaille in the 18th century, and is counted among the 88 modern constellations. Pyxis is completely visible from south of 53 degrees north, with its best evening-sky visibility in February. The plane of the Milky Way passes through Pyxis, a faint constellation, its three brightest stars—Alpha, Beta and Gamma Pyxidis—are in a rough line. At magnitude 3.68, Alpha is the constellations brightest star and it is a blue-white star around 22,000 times as luminous as the Sun. Near Alpha is T Pyxidis, a recurrent nova that has flared up to magnitude 7 every few decades, three star systems have planets, all discovered by doppler spectroscopy. In ancient Chinese astronomy, Alpha, Beta and Gamma Pyxidis formed part of Tianmiao and he devised fourteen new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe. All but one honoured instruments that symbolised the Age of Enlightenment, Lacaille Latinised the name to Pixis Nautica on his 1763 chart. The Ancient Greeks identified the four stars of Pyxis as the mast of the great ship Argo Navis. Covering 220.8 square degrees and hence 0. 535% of the sky and its position in the Southern Celestial Hemisphere means that the whole constellation is visible to observers south of 52°N. It is most visible in the sky in February and March. A small constellation, it is bordered by Hydra to the north, Puppis to the west, Vela to the south, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Pyx. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of eight sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 8h 27. 7m and 9h 27. 6m, while the coordinates are between −17. 41° and −37. 29°. Lacaille gave Bayer designations to ten stars now named Alpha to Lambda Pyxidis, skipping the Greek letters iota, Pyxis is a faint constellation, its three brightest stars—Alpha, Beta and Gamma Pyxidis—form a rough line. Overall, there are 41 stars within the borders with apparent magnitudes brighter than or equal to 6.5. With an apparent magnitude of 3.68, Alpha Pyxidis is the brightest star in the constellation. Located 880 ±30 light-years distant from Earth, it is a giant star of spectral type B1. 5III that is around 22,000 times as luminous as the Sun and has 9.4 ±0.7 times its diameter
Pyxis
–
Pyxis can be seen overlying the mast of Argo Navis
Pyxis
–
List of stars in Pyxis
Pyxis
–
Hubble Space Telescope picture of T Pyxidis, showing ejected material from past eruptions
Pyxis
–
The planetary nebula NGC 2818, imaged by the Hubble telescope
90.
Sagitta
–
Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for arrow, and it should not be confused with the larger constellation Sagittarius, although Sagitta is an ancient constellation, it has no star brighter than 3rd magnitude and has the third-smallest area of all constellations. It was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, located to the north of the equator, Sagitta can be seen from every location on Earth except within the Antarctic circle. The red giant Gamma Sagittae is the constellations brightest star, with an apparent magnitude of 3.47, two star systems have been found to have planets. Covering 79.9 square degrees and hence 0. 194% of the sky and its position in the Northern Celestial Hemisphere means that the whole constellation is visible to observers north of 69°S. It is bordered by Vulpecula to the north, Hercules to the west, Aquila to the south, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Sge. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of twelve segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 18h 57. 2m and 20h 20. 5m, while the coordinates are between 16. 08° and 21. 64°. Johann Bayer gave Bayer designations to eight stars, labelling them Alpha to Theta, what was viewed by Bayer, Friedrich Wilhelm Argelander and Heis as a single star Theta was in fact three stars, and is now equated to HR7705. John Flamsteed added the letters x, y and z to 13,14 and 15 Sagittae in his Catalogus Britannicus, all three were dropped by Bevis and Baily. In his Uranometria, Bayer depicted Alpha, Beta and Epsilon Sagittae as the fins of the arrow, also known as Sham, Alpha is a yellow bright giant star of spectral class G1 II, magnitude 3.82. Zeta Sagittae is a system, approximately 326 light-years from Earth. FG Sagittae is a highly luminous star around 8000 light years distant from Earth. WR124 is a Wolf-Rayet star moving at great speed surrounded by a nebula of ejected gas, HD183143 is a remote blue-white star that has been described as a blue supergiant or hypergiant. It is an Alpha Cygni variable, R Sagittae is a member of the rare RV Tauri variable class of star. It ranges in magnitude from 8.2 to 10.4, S Sagittae is a Classical Cepheid variable that varies from magnitude 5.24 to 6.04 in 8.38 days. It is a yellow-white supergiant that varies between spectral types F6Ib and G5Ib, around 6 or 7 times as massive and 3500 time as luminous as the Sun, it is located around 2300 light-years away from Earth. Located near 18 Sagittae is V Sagittae, WZ Sagittae is a dwarf nova composed of a white dwarf and low mass star companion
Sagitta
–
The constellation Sagitta as it can be seen by the naked eye.
Sagitta
–
List of stars in Sagitta
Sagitta
–
Sagitta can be seen above Aquila in this plate from Urania's Mirror (1825).
91.
Sagittarius (constellation)
–
Sagittarius is one of the constellations of the zodiac. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy and its name is Latin for the archer, and its symbol is, a stylized arrow. Sagittarius is commonly represented as a centaur pulling-back a bow and it lies between Scorpius and Ophiuchus to the west and Capricornus to the east. The center of the Milky Way lies in the westernmost part of Sagittarius, as seen from the northern hemisphere, the constellations brighter stars form an easily recognizable asterism known as the Teapot. The stars δ Sgr, ε Sgr, ζ Sgr, and φ Sgr form the body of the pot, λ Sgr is the point of the lid, γ2 Sgr is the tip of the spout and these same stars originally formed the bow and arrow of Sagittarius. Marking the bottom of the teapots handle (or the shoulder area of the archer, are the bright star Zeta Sagittarii, named Ascella, and the fainter Tau Sagittarii. The constellation as a whole is often depicted as having the appearance of a stick-figure archer drawing its bow. Sagittarius famously points its arrow at the heart of Scorpius, represented by the reddish star Antares, following the direct line formed by Delta Sagittarii and Gamma2 Sagittarii leads nearly directly to Antares. Fittingly, Sagittarii is Alnasl, the Arabic word for arrowhead, and Delta Sagittarii is called Kaus Media, Kaus Media bisects Lambda Sagittarii and Epsilon Sagittarii, whose names Kaus Borealis and Kaus Australis refer to the northern and southern portions of the bow, respectively. α Sgr despite having the alpha appellation, is not the brightest star of the constellation, instead, the brightest star is Epsilon Sagittarii, at magnitude 1.85. Sigma Sagittarii is the constellations second-brightest star at magnitude 2.08, Nunki is a B2V star approximately 260 light years away. Nunki is a Babylonian name of origin, but thought to represent the sacred Babylonian city of Eridu on the Euphrates. Zeta Sagittarii, with apparent magnitude 2.61 of A2 spectra, is actually a star whose two components have magnitudes 3.3 and 3.5. Delta Sagittarii, is a K2 spectra star with magnitude 2.71 and only 85 light years from Earth. Eta Sagittarii is a star with component magnitudes of 3.18 and 10, while Pi Sagittarii is actually a triple system whose components have magnitudes 3.7,3.8. The Bayer designation Beta Sagittarii is shared by two systems, β¹ Sagittarii, with apparent magnitude 3.96, and β² Sagittarii. The two stars are separated by 0. 36° in the sky and are 378 light years from earth, Beta Sagittarii, located at a position associated with the forelegs of the centaur, has the traditional name Arkab, meaning achilles tendon. Nova Sagittarii 2015 No.2 was discovered on March 15,2015, by John Seach of Chatsworth Island, NSW and it lies near the center of the constellation
Sagittarius (constellation)
–
The "Teapot" asterism is in Sagittarius. The Milky Way is the "steam" coming from the spout.
Sagittarius (constellation)
–
List of stars in Sagittarius
Sagittarius (constellation)
–
The constellation Sagittarius as it can be seen with the naked eye.
Sagittarius (constellation)
–
The Omega Nebula, also known as the Horseshoe or Swan Nebula.
92.
Sculptor (constellation)
–
Sculptor is a small and faint constellation in the southern sky. It was introduced by Nicolas Louis de Lacaille in the 18th century and he originally named it Apparatus Sculptoris, but the name was later shortened. The region to the south of Cetus and Aquarius had been named by Aratus in 270 BCE as The Waters – an area of scattered faint stars with two brighter stars standing out, professor of astronomy Bradley Schaefer has proposed that these stars were most likely Alpha and Delta Sculptoris. He named all but one in honour of instruments that symbolised the Age of Enlightenment, Sculptor is a small constellation bordered by Aquarius and Cetus to the north, Fornax to the east, Phoenix to the south, Grus to the southwest, and Piscis Austrinus to the west. The bright star Fomalhaut is nearby, the three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Scl. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 6 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 23h 06. 4m and 01h 45. 5m, while the coordinates are between −24. 80° and −39. 37°. The whole constellation is visible to observers south of latitude 50°N, no stars brighter than 3rd magnitude are located in Sculptor. This is explained by the fact that Sculptor contains the south pole where stellar density is very low. Overall, there are 52 stars within the constellations borders brighter than or equal to apparent magnitude 6.5, the brightest star is Alpha Sculptoris, an SX Arietis-type variable star with a spectral type B7IIIp and an apparent magnitude of 4.3. It is 780 ±30 light-years distant from Earth, R Sculptoris is a red giant that has been found to be surrounded by spirals of matter likely ejected around 1800 years ago. The constellation also contains the Sculptor Dwarf, a galaxy which is a member of the Local Group, as well as the Sculptor Group. The Sculptor Galaxy, a spiral galaxy and the largest member of the group. Another prominent member of the group is the irregular galaxy NGC55, one unique galaxy in Sculptor is the Cartwheel Galaxy, at a distance of 500 million light-years. The result of a merger around 300 million years ago, the Cartwheel Galaxy has a core of older, yellow stars, and a ring of younger, blue stars. The smaller galaxy in the collision is now incorporated into the core, the shock waves from the collision sparked extensive star formation in the outer ring. Sculptor was a United States Navy Crater class cargo ship named after the constellation, notes Citations Sources Sculptor Constellation at Constellation Guide
Sculptor (constellation)
–
Curious spiral around red giant star R Sculptoris.
Sculptor (constellation)
–
List of stars in Sculptor
93.
Serpens
–
Serpens is a constellation of the northern hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy and it is unique among the modern constellations in being split into two non-contiguous parts, Serpens Caput to the west and Serpens Cauda to the east. Between these two lies the constellation of Ophiuchus, the Serpent-Bearer. In figurative representations, the body of the serpent is represented as passing behind Ophiuchus between Mu Serpentis in Serpens Caput and Nu Serpentis in Serpens Cauda. The brightest star in Serpens is the red giant star Alpha Serpentis, or Unukalhai, in Serpens Caput, also located in Serpens Caput are the naked-eye globular cluster Messier 5 and the naked-eye variables R Serpentis and Tau4 Serpentis. Part of the Milky Ways galactic plane passes through Serpens Cauda, the nebula measures 70 light-years by 50 light-years and contains the Pillars of Creation, three dust clouds that became famous for the image taken by the Hubble Space Telescope. In Greek mythology, Serpens represents a snake held by the healer Asclepius, represented in the sky by the constellation Ophiuchus, Asclepius once killed a snake, but the animal was subsequently resurrected after a second snake placed a revival herb on it before its death. As snakes shed their skin every year, they were known as the symbol of rebirth in ancient Greek society, although this is likely the logic for Serpens presence with Ophiuchus, the true reason is still not fully known. Sometimes, Serpens was depicted as coiling around Ophiuchus, but the majority of atlases showed Serpens passing either behind Ophiuchus body or between his legs. In some ancient atlases, the constellations Serpens and Ophiuchus were depicted as two separate constellations, although often they were shown as a single constellation. One notable figure to depict Serpens separately was Johann Bayer, thus, when Eugène Delporte established modern constellation boundaries in the 1920s, he elected to depict the two separately. However, this posed the problem of how to disentangle the two constellations, with Deporte deciding to split Serpens into two areas—the head and the tail—separated by the continuous Ophiuchus. These two areas known as Serpens Caput and Serpens Cauda, caput being the Latin word for head. In Chinese astronomy, most of the stars of Serpens represented part of a wall surrounding a marketplace, known as Tianshi, Serpens also contains a few Chinese constellations. Two stars in the tail represented part of Shilou, the tower with the market office, another star in the tail represented Liesi, jewel shops. One star in the head marked Tianru, the crown princes wet nurse, there were two serpent constellations in Babylonian astronomy, known as Mušḫuššu and Bašmu. It appears that Mušḫuššu was depicted as a hybrid of a dragon, a lion and a bird, Bašmu was a horned serpent and roughly corresponds to the Ὄφις constellation of Eudoxus of Cnidus on which the Ὄφις of Ptolemy is based. Serpens is the one of the 88 modern constellations to be split into two disconnected regions in the sky, Serpens Caput and Serpens Cauda
Serpens
–
Serpens held by Ophiuchus, as depicted in Urania's Mirror, a set of constellation cards published in London c. 1825. Above the tail of the serpent is the now-obsolete constellation Taurus Poniatovii while below it is Scutum
Serpens
–
List of stars in Serpens
Serpens
–
The constellation Serpens (Caput) as it can be seen by the naked eye
Serpens
–
The constellation Serpens (Cauda) as it can be seen by the naked eye
94.
Triangulum
–
Triangulum is a small constellation in the northern sky. Its name is Latin for triangle, derived from its three brightest stars, which form a long and narrow triangle, known to the ancient Babylonians and Greeks, Triangulum was one of the 48 constellations listed by the 2nd century astronomer Ptolemy. The celestial cartographers Johann Bayer and John Flamsteed catalogued the constellations stars, giving six of them Bayer designations. The white stars Beta and Gamma Trianguli, of apparent magnitudes 3.00 and 4.00, respectively, form the base of the triangle and the yellow-white Alpha Trianguli, of magnitude 3.41, the apex. Iota Trianguli is a double star system, and there are three star systems with known planets located in Triangulum. The constellation contains several galaxies, the brightest and nearest of which is the Triangulum Galaxy or Messier 33—a member of the Local Group, the first quasar ever observed, 3C48, also lies within Triangulums boundaries. In the Babylonian star catalogues, Triangulum, together with Gamma Andromedae and it is notable as the first constellation presented on a pair of tablets containing canonical star lists that were compiled around 1000 BC, the MUL. APIN. The Plough was the first constellation of the Way of Enlil—that is, the northernmost quarter of the Suns path and its first appearance in the pre-dawn sky in February marked the time to begin spring ploughing in Mesopotamia. The Ancient Greeks called Triangulum Deltoton, as the constellation resembled an upper-case Greek letter delta and it was transliterated by Roman writers, then later Latinised as Deltotum. Eratosthenes linked it with the Nile Delta, while the Roman writer Hyginus associated it with the island of Sicily, formerly known as Trinacria due to its shape. It was also called Sicilia, because the Romans believed Ceres, patron goddess of Sicily, Greek astronomers such as Hipparchos and Ptolemy called it Trigonon, and later, it was Romanized as Trigonum. Other names referring to its shape include Tricuspis and Triquetrum, Alpha and Beta Trianguli were called Al Mīzān, which is Arabic for The Scale Beam. Later, the 17th-century German celestial cartographer Johann Bayer called the constellation Triplicitas and Orbis terrarum tripertitus, triangulus Septentrionalis was a name used to distinguish it from Triangulum Australe, the Southern Triangle. The smaller constellation was not recognised by the International Astronomical Union when the constellations were established in the 1920s. A small constellation, Triangulum is bordered by Andromeda to the north and west, Pisces to the west and south, Aries to the south, the centre of the constellation lies halfway between Gamma Andromedae and Alpha Arietis. The three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is Tri, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined as a polygon of 14 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 01h 31. 3m and 02h 50. 4m, while the coordinates are between 25. 60° and 37. 35°. Covering 132 square degrees and 0. 320% of the night sky, Bayer catalogued five stars in the constellation, giving them the Bayer designations Alpha to Epsilon
Triangulum
–
The constellation Triangulum as it can be seen by the naked eye.
Triangulum
–
List of stars in Triangulum
Triangulum
–
The peculiar asymmetry of NGC 949.
95.
Triangulum Australe
–
Triangulum Australe is a small constellation in the far Southern Celestial Hemisphere. Its name is Latin for the triangle, which distinguishes it from Triangulum in the northern sky and is derived from the almost equilateral pattern of its three brightest stars. It was first depicted on a globe as Triangulus Antarcticus by Petrus Plancius in 1589. The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the stars their Bayer designations in 1756. Alpha Trianguli Australis, known as Atria, is an orange giant. Completing the triangle are the two main sequence stars Beta and Gamma Trianguli Australis. Although the constellation lies in the Milky Way and contains many stars, notable features include the open cluster NGC6025 and planetary nebula NGC5979. Italian navigator Amerigo Vespucci explored the New World at the beginning of the 16th century and he learnt to recognize the stars in the southern hemisphere and made a catalogue for his patron king Manuel I of Portugal, which is now lost. As well as the catalogue, Vespucci wrote descriptions of the southern stars and this was sent to his patron in Florence, Lorenzo di Pierfrancesco de Medici, and published as Mundus Novus in 1504. His student Petrus Keyzer, along with Dutch explorer Frederick de Houtman, Triangulum Australe was more accurately depicted in Johann Bayers celestial atlas Uranometria in 1603, where it was also given its current name. Also depicting it as a level, German Johann Bode gave it the alternate name of Libella in his Uranographia. German poet and author Philippus Caesius saw the three stars as representing the Three Patriarchs, Abraham, Isaac and Jacob. The Wardaman people of the Northern Territory in Australia perceived the stars of Triangulum Australe as the tail of the Rainbow Serpent, overhead in October, the Rainbow Serpent gives Lightning a nudge to bring on the wet season rains in November. Triangulum Australe is a constellation bordered by Norma to the north, Circinus to the west, Apus to the south. It lies near the Pointers, with only Circinus in between, the constellation is located within the Milky Way, and hence has many stars. A roughly equilateral triangle, it is easily identifiable, Triangulum Australe lies too far south in the celestial southern hemisphere to be visible from Europe, yet is circumpolar from most of the southern hemisphere. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is TrA, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 18 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 14h 56. 4m and 17h 13. 5m, while the coordinates are between −60. 26° and −70. 51°
Triangulum Australe
–
ESO 69-6, two merging galaxies with prominent long tails, photographed by the Hubble Space Telescope
Triangulum Australe
–
List of stars in Triangulum Australe
96.
Tucana
–
Tucana is a constellation of stars in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the sixteenth century by Petrus Plancius from the observations of Pieter Dirkszoon Keyser. Tucana first appeared on a 35-centimetre-diameter celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayers star atlas Uranometria of 1603, french explorer and astronomer Nicolas Louis de Lacaille gave its stars Bayer designations in 1756. The constellations Tucana, Grus, Phoenix and Pavo are collectively known as the Southern Birds, Tucana is not a prominent constellation as all of its stars are third magnitude or fainter, the brightest is Alpha Tucanae with an apparent visual magnitude of 2.87. Beta Tucanae is a system with six member stars, while Kappa is a quadruple system. Five star systems have found to have exoplanets to date. The constellation contains 47 Tucanae, one of the brightest globular clusters in the sky and it first appeared on a 35-centimetre-diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius. The first depiction of this constellation in an atlas was in the German cartographer Johann Bayers Uranometria of 1603. Both Plancius and Bayer depict it as a toucan, a 1603 celestial globe by Willem Blaeu depicts it with a casque. Tucana and the nearby constellations Phoenix, Grus and Pavo are collectively called the Southern Birds, irregular in shape, Tucana is bordered by Hydrus to the east, Grus and Phoenix to the north, Indus to the west and Octans to the south. Covering 295 square degrees, it ranks 48th of the 88 constellations in size, the recommended three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Tuc. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 10 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 22h 08. 45m and 01h 24. 82m, while the coordinates are between −56. 31° and −75. 35°. Although he depicted Tucana on his chart, Bayer did not assign its stars Bayer designations, mu Tucanae was dropped by Francis Baily, who felt the star was too faint to warrant a designation, and Kappas two components came to be known as Kappa1 and Kappa2. The layout of the stars of Tucana has been likened to a kite. Within the constellations boundaries are around 80 stars brighter than an apparent magnitude of 7, at an apparent magnitude of 2.86, Alpha Tucanae is the brightest star in the constellation and marks the toucans head. It is a subgiant of spectral type K3III around 199 light-years distant from the Solar System. A cool star with a temperature of 4300 K, it is 424 times as luminous as the sun and 37 times its diameter
Tucana
–
The "southern birds" as seen in Johann Bayer 's Uranometria. Tucana (as "Toucan") is in the middle.
Tucana
–
List of stars in Tucana
Tucana
–
Most of the Small Magellanic Cloud lies within Tucana.
Tucana
–
Globular Cluster 47 Tuc. Credit ESO
97.
Vela (constellation)
–
Vela is a constellation in the southern sky. Its name is Latin for the sails of a ship, and it was part of a larger constellation, the ship Argo Navis. With an apparent magnitude of 1.8, its brightest star is the hot blue multiple star Gamma Velorum, Delta and Kappa Velorum, together with Epsilon and Iota Carinae, form the asterism known as the False Cross. 1. 95-magnitude Delta is actually a triple or quintuple star system, german cartographer Johann Bayer depicted the constellation on his Uranometria of 1603, and gave the stars Bayer designations from Alpha to Omega. However, his chart was inaccurate as the constellation was not visible from the Northern Hemisphere, Argo was more accurately charted and subdivided in 1752 by the French astronomer Nicolas Louis de Lacaille, forming Carina, Vela, and Puppis. Despite the division, Lacaille kept Argos Bayer designations, therefore, Carina has the Alpha, Beta and Epsilon, Vela has Gamma and Delta, Puppis has Zeta, and so on. Vela is bordered by Antlia and Pyxis to the north, Puppis to the northwest, Carina to the south and southwest, covering 500 square degrees, it ranks 32nd of the 88 modern constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is Vel, the official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 14 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 08h 13. 3m and 11h 05. 5m, while the coordinates are between −37. 16° and −57. 17°. The brightest star in the constellation, Gamma Velorum, is a multiple star system. The brighter component, known as Gamma2 Velorum or Suhail, shines as a star of apparent magnitude 1.83. It is a spectroscopic binary made up of two hot blue stars orbiting each other every 78.5 days and separated by somewhere between 0.8 and 1.6 Astronomical Units. The second component is a rare example of hot star known as a Wolf–Rayet star. It has a temperature of 57,000 and is around 170,000 times as luminous as our sun. Gamma1 is a star of spectral type B2III and apparent magnitude 4.3. The two pairs are separated by 41 arcseconds, easily separable in binoculars, parallax measurements give a distance of 1,116 light years, meaning that they are at least 12,000 AU apart. Further afield are 7. 3-magnitude Gamma Velorum C and 9.4 magnitude Gamma Velorum D, the next brightest star is Delta Velorum, also a multiple star system and one of the brightest eclipsing binaries in the sky. Appearing as a star of magnitude 1.95, Delta is actually a triple or possibly quintuple star system located around 80 light-years from the Solar System
Vela (constellation)
–
Deep-sky photograph of NGC 3132, also known as the Eight-Burst or Southern Ring Nebula. © NASA.
Vela (constellation)
–
List of stars in Vela
98.
Virgo (constellation)
–
Virgo is one of the constellations of the zodiac. Its name is Latin for virgin, and its symbol is ♍, lying between Leo to the west and Libra to the east, it is the second largest constellation in the sky. It can be found through its brightest star, Spica. The bright Spica makes it easy to locate Virgo, as it can be found by following the curve of the Big Dipper/Plough to Arcturus in Boötes and continuing from there in the same curve. Due to the effects of precession, the First Point of Libra and this is one of the two points in the sky where the celestial equator crosses the ecliptic This point will pass into the neighbouring constellation of Leo around the year 2440. Besides Spica, other stars in Virgo include β Virginis, γ Vir, δ Virginis. Other fainter stars that were given names are ζ Virginis, η Virginis, ι Virginis. The star 70 Virginis has one of the first known extrasolar planetary systems with one confirmed planet 7.5 times the mass of Jupiter, the star Chi Virginis has one of the most massive planets ever detected, at a mass of 11.1 times that of Jupiter. The sun-like star 61 Virginis has three planets, one is a super-Earth and two are Neptune-mass planets, SS Virginis is a variable star with a noticeable red color. It varies in magnitude from a minimum of 9.6 to a maximum of 6.0 over a period of one year. There are 35 verified exoplanets orbiting 29 stars in Virgo, including PSR B1257+12,70 Virginis, Chi Virginis,61 Virginis, NY Virginis, and 59 Virginis. Because of the presence of a cluster within its borders 5° to 12° west of ε Vir. Some examples are Messier 49, Messier 58, Messier 59, Messier 60, Messier 61, Messier 84, Messier 86, Messier 87, Messier 89, a noted galaxy that is not part of the cluster is the Sombrero Galaxy, an unusual spiral galaxy. It is located about 10° due west of Spica, NGC4639 is a face-on barred spiral galaxy located 78 Mly from Earth. Its outer arms have a number of Cepheid variables, which are used as standard candles to determine astronomical distances. Because of this, astronomers used several Cepheid variables in NGC4639 to calibrate type 1a supernovae as standard candles for more distant galaxies, Virgo possesses several galaxy clusters, one of which is HCG62. A Hickson Compact Group, HCG62 is at a distance of 200 Mly from Earth and it has a heterogeneous halo of extremely hot gas, posited to be due to the active galactic nucleus at the core of the central elliptical galaxy. M87 is the largest galaxy in the Virgo cluster, and is at a distance of 60 Mly from Earth and it is a major radio source, partially due to its jet of electrons being flung out of the galaxy by its central supermassive black hole
Virgo (constellation)
–
The constellation Virgo.
Virgo (constellation)
–
List of stars in Virgo
Virgo (constellation)
–
Virgo as depicted in Urania's Mirror, a set of constellation cards published in London c.1825.
99.
Argo Navis
–
Argo Navis, or simply Argo, was a large constellation in the Earths southern sky that has since been divided into three constellations. It was identified with the Argo, the used by Jason. The genitive was Argus Navis, abbreviated Arg, flamsteed and other early modern astronomers called the constellation just Navis, genitive Navis, abbreviated Nav. Due to precession, the stars of Argo have been shifted farther south since Classical times, the original constellation was found low near the southern horizon of the Mediterranean sky. The ship became visible in springtime and sailed westward, skimming along the southern horizon, the ancient Greeks identified it with the ship sailed by Jason and the Argonauts to Colchis in search of the Golden Fleece. Argo Navis is the one of the 48 constellations listed by the 2nd century astronomer Ptolemy that is no longer officially recognized as a constellation. It was unwieldy due to its enormous size, similarly, faint non-lettered stars were listed only as in Argûs. The final breakup and abolition of Argo Navis was proposed by Sir John Herschel in 1841 and again in 1844, but it was not formalised until 1930 when the IAU defined the 88 modern constellations. Lacailles designations were kept in the three separate constellations, so Carina has α, β and ε, Vela has γ and δ, Puppis has ζ, the constellation Pyxis occupies an area which in antiquity was considered part of Argos mast. Some authors state that Pyxis was part of the Greek conception of Argo Navis, lacaille considered it a separate constellation, representing one of the modern scientific instruments he placed among the constellations. Pyxis was listed separately, among his 14 new constellations, lacaille assigned Bayer designations to Pyxis separate from those of Argo, and his illustration shows an isolated instrument not related to the figure of the ship. In 1844 John Herschel suggested formalizing the mast as a new constellation, Malus, to replace Lacailles Pyxis, the Māori had several names for what was the constellation Argo, including Te Waka-o-Tamarereti, Te Kohi-a-Autahi, and Te Kohi. Asterism List of stars in Argo Navis Starry Night Photography, Argo Navis Image Star Tales – Argo Navis Warburg Institute Iconographic Database – Argo
Argo Navis
–
The constellation Argo Navis drawn by Johannes Hevelius
100.
Anser (constellation)
–
Vulpecula /vʌlˈpɛkjʊlə/ is a faint constellation in the northern sky. Its name is Latin for little fox, although it is known simply as the fox. It was identified in the century, and is located in the middle of the Summer Triangle. There are no stars brighter than 4th magnitude in this constellation, the brightest star in Vulpecula is Alpha Vulpeculae, a magnitude 4. 44m red giant at a distance of 297 light-years. The star is a binary that can be split using binoculars. The star also carries the traditional name Anser, which refers to the goose the little fox holds in its jaws,23 Vulpeculae is the second brightest star in the constellation. In 1967, the first pulsar, PSR B1919+21, was discovered in Vulpecula by Jocelyn Bell, supervised by Antony Hewish, while they were searching for scintillation of radio signals of quasars, they observed pulses which repeated with a period of 1.3373 seconds. Terrestrial origin of the signal was ruled out because the time it took the object to reappear was a day instead of a solar day. This anomaly was finally identified as the signal of a rotating neutron star. Fifteen years after the first pulsar was discovered, the first millisecond pulsar, PSR B1937+21, was discovered in Vulpecula. Vulpecula is also home to HD189733 b, one of the closest extrasolar planet currently being studied by the Spitzer Space Telescope, on 12 July 2007 the Financial Times reported that the chemical signature of water vapour was detected in the atmosphere of this planet. The Dumbbell Nebula, is a large, bright planetary nebula which was discovered by the French astronomer Charles Messier in 1764 as the very first object of its kind. It can be seen with binoculars in a dark sky location. A telescope reveals its double-lobed shape, similar to that of an hourglass, brocchis Cluster is an asterism formerly thought to be an open cluster. It is also called the Coathanger because of its distinctive star pattern when viewed with binoculars or a low power telescope, NGC7052 is an edge-on spiral galaxy in Vulpecula at a distance of 214 million light-years from Earth. It has a dusty disk with a diameter of 3700 light-years. Astronomers surmise that the disk is the remnant of a galaxy that merged with NGC7052. Jets can be seen emanating from the galaxy, and it has very strong radio emissions and this means that it is also classified as a radio galaxy
Anser (constellation)
–
The constellation Vulpecula as it can be seen by the naked eye.
Anser (constellation)
–
List of stars in Vulpecula
Anser (constellation)
–
The Dumbbell Nebula
Anser (constellation)
–
The constellation, under the full name of "Vulpecula and Anser", can be seen on the bottom of this c. 1825 star map from Urania's Mirror.
101.
Antinous (constellation)
–
Antinous is an obsolete constellation no longer in use by astronomers, having been merged into Aquila, which it bordered to the North. The constellation was created by the emperor Hadrian in 132, according to legend, Hadrian was told by an oracle that only the death of his most beloved person would save him from a great danger. Sure enough, Antinous, a beautiful youth loved by Hadrian, for his memory Hadrian identified an asterism in the sky with Antinous
Antinous (constellation)
–
Constellations Antinous (below) and Aquila ("Adler" in German). From Johann Bode 's Vorstellung der Gestirne (1782)
Antinous (constellation)
–
Seen in Urania's Mirror (1825).
102.
Cerberus (constellation)
–
Cerberus is an obsolete constellation created by Hevelius, whose stars are now included in the constellation Hercules. It was depicted as a snake that Hercules is holding in his hand. The constellation is no longer in use and this constellation figure typified the serpent. Infesting the country around Taenarum the Μέτωπον of Greece, the modern Cape Matapan, the presence of Cerberus at Taenarum is mentioned by Strabo, Statius, and Seneca the Younger. John Senex combined this constellation with the obsolete constellation Ramus Pomifer. Ian Ridpaths Star Tales, Cerberus http, //www. pa. msu. edu/people/horvatin/Astronomy_Facts/obsolete_pages/cerberus. htm
Cerberus (constellation)
–
The "Cerberus et Ramus" combination of Cerberus and Ramus Pomifer can be seen in this plate from Urania's Mirror (c. 1825).
103.
Felis (constellation)
–
Felis was a constellation created by French astronomer Jérôme Lalande in 1799. He chose the name partly because, as a cat lover and it was between the constellations of Antlia and Hydra. This constellation was first depicted in the Uranographia sive Astrorum Descriptio of Johann Elert Bode, former constellations Felis constellation, Ian Ridpaths Star Tales
Felis (constellation)
–
Felis
104.
Lilium (constellation)
–
Musca Borealis was a constellation, now discarded, located between the constellations of Aries and Perseus. It was originally called Apes by Petrus Plancius when he created it in 1612 and it was made up of a small group of stars, now called 33 Arietis,35 Arietis,39 Arietis, and 41 Arietis, in the north of the constellation of Aries. The brightest star is now known as 41 Arietis, at magnitude 3.63, it is a blue-white main sequence star of spectral type B8V around 166 light-years distant. 39 Arietis is a giant star of magnitude 4.51. The constellation was renamed Vespa by Jakob Bartsch in 1624, the renaming by Bartsch may have been intended to avoid confusion with another constellation, created by Plancius in 1598, that was called Apis by Bayer in 1603. Plancius called this earlier constellation Muia in 1612, and it had been called Musca by Blaeu in 1602, in 1679 Augustin Royer used these stars for his constellation Lilium. It was first described as Musca by Hevelius in his catalogue of 1690, subsequent astronomers renamed it into Musca Borealis, to distinguish it from the southern fly, Musca Australis. This constellation is no longer in use, the stars it contained are now included in Aries, the Southern Fly, Musca Australis, is now simply known as Musca
Lilium (constellation)
–
Constellation Musca in Johannes Hevelius' atlas (1690). In this atlas, constellations are shown as they would appear on a globe, i.e. back to front by comparison with their appearance in the sky.
Lilium (constellation)
–
In Urania's Mirror (1825).
105.
Mons Maenalus
–
Mons Maenalus was a constellation created by Johannes Hevelius in 1687. It was located between the constellations of Boötes and Virgo, and depicts a mountain in Greece that the herdsman is stepping upon and it was increasingly considered obsolete by the latter half of the 19th century. Its brightest star is 31 Boötis, a G-type giant of apparent magnitude 4. 86m
Mons Maenalus
–
Plate from Hevelius' Uranographica; Mons Mænalus is in the lower right, under Boötes.
Mons Maenalus
–
Map of the constellation Mons Maenalus
106.
Musca Borealis
–
Musca Borealis was a constellation, now discarded, located between the constellations of Aries and Perseus. It was originally called Apes by Petrus Plancius when he created it in 1612 and it was made up of a small group of stars, now called 33 Arietis,35 Arietis,39 Arietis, and 41 Arietis, in the north of the constellation of Aries. The brightest star is now known as 41 Arietis, at magnitude 3.63, it is a blue-white main sequence star of spectral type B8V around 166 light-years distant. 39 Arietis is a giant star of magnitude 4.51. The constellation was renamed Vespa by Jakob Bartsch in 1624, the renaming by Bartsch may have been intended to avoid confusion with another constellation, created by Plancius in 1598, that was called Apis by Bayer in 1603. Plancius called this earlier constellation Muia in 1612, and it had been called Musca by Blaeu in 1602, in 1679 Augustin Royer used these stars for his constellation Lilium. It was first described as Musca by Hevelius in his catalogue of 1690, subsequent astronomers renamed it into Musca Borealis, to distinguish it from the southern fly, Musca Australis. This constellation is no longer in use, the stars it contained are now included in Aries, the Southern Fly, Musca Australis, is now simply known as Musca
Musca Borealis
–
Constellation Musca in Johannes Hevelius' atlas (1690). In this atlas, constellations are shown as they would appear on a globe, i.e. back to front by comparison with their appearance in the sky.
Musca Borealis
–
In Urania's Mirror (1825).
107.
Robur Carolinum
–
Robur Carolinum was a constellation created by the English astronomer Edmond Halley in 1679. The name refers to the Royal Oak where Charles II was said to have hidden from the troops of Oliver Cromwell after the Battle of Worcester and it was between the constellations of Centaurus and Carina, extending into half of Vela. Robur Carolinum as a constellation never gained popularity, probably because it used the star Eta Carinae and the Eta Carinae Nebula, nicolas Louis de Lacaille also complained bitterly that it took some of the finest stars from Argo Navis. Its brightest star was Beta Carinae or Miaplacidus, which was known as α Roburis or α Roburis Carolii
Robur Carolinum
–
Robur Carolinum in Johannes Hevelius 's Uranographia.
108.
Rangifer (constellation)
–
Rangifer was a small constellation between the constellations of Cassiopeia and Camelopardalis. It is also known as Tarandus, both words mean reindeer in Latin. Rangifer is the name of the reindeer, and tarandus is the specific name. The constellation Rangifer was created by the French astronomer Pierre Charles Le Monnier in 1736 to commemorate the expedition of Maupertuis to Lapland, geodetical observations from the expedition proved Earths oblateness. The constellation is no longer in use, Rangifer, the reindeer, Ian Ridpaths Star Tales Tarandus vel Rangifer, the reindeer, Shane Horvatin
Rangifer (constellation)
–
Tarandus and the likewise-obsolete constellation of Custos Messium depicted above Camelopardalis.
109.
Telescopium Herschelii
–
Telescopium Herschelii, also formerly known as Tubus Hershelli Major, is a former constellation in the northern celestial hemisphere. Maximilian Hell established it in 1789 to honour Sir William Herschels discovery of the planet Uranus and it fell out of use by the end of the 19th century. Psi2 Aurigae at apparent magnitude 4.8 was the constellations brightest star and it was one of two constellations created by Maximilian Hell in 1789 to honour the famous English astronomer Sir William Herschels discovery of the planet Uranus. Named Tubus Hershelli Major by Hell, it was located in the constellation Auriga near the border to Lynx and Gemini and its sibling was Tubus Hershelli Minor, which lay between Orion and Taurus. The two telescopes lay near Zeta Tauri, near where the planet Uranus was first spotted, johann Elert Bode renamed the constellation Telescopium Herschelii and omitted the smaller telescope constellation in his 1801 Uranographia star atlas. In his atlas, the constellation depicted Herschels earlier 7-foot telescope and it was ignored by some celestial cartographers such as Argelander in 1843, Proctor in 1876, Rosser in 1879 and Pritchard in 1885, yet did appear in two works of the 1890s. However, it was noted by Allen in 1899 that it was becoming obsolete, in 1930, when the official borders of the constellations were drawn up, its stars were absorbed into Auriga, Gemini and Lynx. Psi2 Aurigae, with an apparent magnitude of 4.8, was the brightest star in the constellation, located 420 ±20 light-years distant from earth, it is an orange giant of spectral type K3III. Other stars belonging to the constellation include Psi4, Psi5, Psi7,63,64,65 and 66 Aurigae, and Omicron Geminorum. Thought to be around 4 billion years old, Psi5 Aurigae is a star of spectral type G0V that is around 1.07 times as massive as the Sun and 1.18 times as wide. It appears to have a disk of dust, known as a debris disk
Telescopium Herschelii
–
Photograph of Telescopium Herschelii with constellations Gemini, Auriga, Perseus and the Pleiades.
Telescopium Herschelii
–
Telescopium Herschelii on a celestial globe at the Herschel Museum of Astronomy, Bath.
Telescopium Herschelii
–
Illustrated in Urania's Mirror (1825), next to Lynx
. doi:10.1051/0004-6361:20078357.
