Cepheus is a constellation in the northern sky, named after Cepheus, a king of Aethiopia in Greek mythology. Cepheus was one of the 48 constellations listed by the second century astronomer Ptolemy, it remains one of the 88 constellations in the modern times; the constellation's brightest star is Alpha Cephei, with an apparent magnitude of 2.5. 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, MY Cephei, VV Cephei, V354 Cephei are among the largest stars known. In addition, Cepheus has the hyperluminous quasar S5 0014+81, which hosts an ultramassive black hole in its core, reported at 40 billion solar masses, about 10,000 times more massive than the central black hole of the Milky Way, making this among the most massive black holes known. Cepheus was the King of Aethiopia, he was married to Cassiopeia and was the father of Andromeda, both of whom are immortalized as modern day constellations along with Cepheus.
Alpha Cephei known as Alderamin, is the brightest star in the constellation, with an apparent magnitude of 2.51. 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. It varies between 3.5 4.4 m over a period of 5 days and 9 hours. The Cepheids are a class of pulsating variable stars, it is a double star. There are three red giants in the constellation. Mu Cephei is known as Herschel's Garnet Star due to its deep red colour, it is a semiregular variable star with a minimum magnitude of 5.1 and a maximum magnitude of 3.4. Its period is 2 years; the star is around 5.64 AU in radius. If it were placed at the center of the Solar System, it would extend to the orbit of Jupiter. 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 minimum magnitude of 5.4 and a maximum magnitude of 4.8, is paired with a blue main sequence star called VV Cephei B.
One of the largest stars in the galaxy, it has a diameter 1,400 times that of the Sun. VV Cephei is an unusually long-period eclipsing binary, but the eclipses, which occur every 20.3 years, are too faint to be observed with the unaided eye. T Cephei 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 diameter of between 329 to 500 solar diameters. There are binary stars in Cepheus. Omicron Cephei is a binary 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 and a secondary of magnitude 7.1. Xi Cephei is 102 light-years from Earth, with a period of 4,000 years, it has a blue-white primary of magnitude 4.4 and a yellow secondary of magnitude 6.5. Kruger 60 is an 11th-magnitude binary star consisting of two red dwarfs; the star system is one of the nearest. NGC 188 is an open cluster that has the distinction of being the closest open cluster to the north celestial pole, as well as one of the oldest-known open clusters.
NGC 6946 is a spiral galaxy in which ten supernovae have been observed, more than in any other galaxy. IC 469 is another spiral galaxy, characterized by a compact nucleus, of oval shape, with perceptible side arms; the nebula NGC 7538 is home to the largest-yet-discovered protostar. NGC 7023 is a reflection nebula with an associated star cluster; the nebula and cluster are located near T Cephei. S 155 known as the Cave Nebula, is a dim and diffuse bright nebula within a larger nebula complex containing emission and dark nebulosity; the quasar 6C B0014+8120 is one of the most powerful objects in the universe, powered by a supermassive black hole equivalent to 40 billion Suns. Cepheus is most depicted as holding his arms aloft, praying for the deities to spare the life of Andromeda, he is depicted as a more regal monarch sitting on his throne. In Chinese astronomy, the stars of the constellation Cepheus are found in two areas: the Purple Forbidden enclosure and the Black Tortoise of the North. In the TV sitcom 3rd Rock from the Sun, the aliens' home planet is stated to be located in a barred spiral galaxy on the Cepheus-Draco border.
One antagonist of the video game Mega Man Star Force is a character named King Cepheus. Contextually, the constellation Cepheus is the one referenced by this name; the Canadian musician Deadmau5 named his song "HR 8938 Cephei" after a star in the constellation. An end-of-game boss in the video game Lovers in a Dangerous Spacetime is called King Cepheus, after the constellation. USS Cepheus and USS Cepheus, United States Navy ships. Cepheus in Chinese astronomy Levy, David H.. Deep Sky Objects. Prometheus Books. ISBN 1-59102-361-0. Ridpath, Ian. Stars and Planets Guide, London. ISBN 978-0-00-725120-9. Princeton University Press, Princeton. ISBN 978-0-691-13556-4. Staal, Julius D. W; the New Patterns in the Sky: Myths and Legends of the Stars, The McDonald and Woodward Publishing Company, ISBN 0-939923-04-1 The Deep Photographic Guide to the Constellations: Cepheus The clickable Ce
Ursa Major is a constellation in the northern sky, whose associated mythology dates back into prehistory. Its Latin name means "greater she-bear", standing as a reference to and in direct contrast with nearby Ursa Minor, the lesser bear. In antiquity, it was one of the original 48 constellations listed by Ptolemy, is now the third largest constellation of the 88 modern constellations. Ursa Major is known from the asterism of its main seven bright stars comprising the "Big Dipper", "the Wagon", "Charles's Wain" or "the Plough", with its stellar configuration mimicking the shape of the "Little Dipper"; the general constellation outline significantly features in numerous world cultures, is used as a symbol of the north. E.g. as the flag of Alaska. The asterism's two brightest stars, named Dubhe and Merak, can be used as the navigational pointer towards the place of the current northern pole star, Polaris in Ursa Minor. Ursa Major is visible throughout the year from most of the northern hemisphere, appears circumpolar above the mid-northern latitudes.
From southern temperate latitudes, the main asterism is invisible, but the southern parts of the constellation can still be viewed. Appearing in the northern sky, Ursa Major occupies a large area covering 1279.66 square degrees or 3.10% of the total sky, making it the third largest constellations in the night sky. Eugène Delporte in 1930, who set the official International Astronomical Union constellation boundaries, formed a 28-sided irregular polygon, which according to the equatorial coordinate system, stretches between the right ascension coordinates of 08h 08.3m and 14h 29.0m and the declination coordinates of +28.30° and +73.14°. Ursa Major borders eight other constellations: Draco to the north and northeast, Boötes to the east, Canes Venatici to the east and southeast, Coma Berenices to the southeast and Leo Minor to the south, Lynx to the southwest and Camelopardalis to the northwest; the three-letter constellation abbreviation'UMa' was adopted by the IAU in 1922. 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.
Like many of its common names allude to, its shape is said to resemble either a ladle, an agricultural plough or wagon. Starting with the "ladle" portion of the dipper and extending clockwise through the handle, these stars are the following: α Ursae Majoris, known by the Arabic name Dubhe, which at a magnitude of 1.79 is the 35th-brightest star in the sky and the second-brightest of Ursa Major. 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," referring to its location as the intersection of the body and tail of the bear. Ε Ursae Majoris, known as Alioth, a name which refers not to a bear but to a "black horse," the name corrupted from the original and mis-assigned to the named Alcor, the naked-eye binary companion of Mizar. Alioth is the brightest star of Ursa Major and the 33rd-brightest in the sky, with a magnitude of 1.76. It is the brightest of the "peculiar A stars," magnetic stars whose chemical elements are either depleted or enhanced, appear to change as the star rotates.
Ζ Ursae Majoris, the second star in from the end of the handle of the Big Dipper, the constellation's fourth-brightest star. Mizar, which means "girdle," forms a famous double star, with its optical companion Alcor, the two of which were termed the "horse and rider" by the Arabs; the ability to resolve the two stars with the naked eye is quoted as a test of eyesight, although 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 common point in Sagittarius. A few other such stars have been identified, 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 known as the North Star or Pole Star. By visually tracing a line from Merak through Dubhe and continuing for 5 units, one's eye will land on Polaris indicating true north.
Another asterism known as the "Three Leaps of the Gazelle" is recognized in Arab culture, a series of three pairs of stars found along the southern border of the constellation. W Ursae Majoris is the prototype of a class of contact binary variable stars, 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
A binary star is a star system consisting of two stars orbiting around their common barycenter. Systems of two or more stars are called multiple star systems; these systems when more distant appear to the unaided eye as a single point of light, are revealed as multiple by other means. Research over the last two centuries suggests that half or more of visible stars are part of multiple star systems; the term double star is used synonymously with binary star. Optical doubles are so called because the two stars appear close together in the sky as seen from the Earth, their "doubleness" depends only on this optical effect. A double star can be revealed as optical by means of differences in their parallax measurements, proper motions, or radial velocities. Most known double stars have not been studied adequately to determine whether they are optical doubles or doubles physically bound through gravitation into a multiple star system. Binary star systems are important in astrophysics because calculations of their orbits allow the masses of their component stars to be directly determined, which in turn allows other stellar parameters, such as radius and density, to be indirectly estimated.
This determines an empirical mass-luminosity relationship from which the masses of single stars can be estimated. Binary stars are detected optically, in which case they are called visual binaries. Many visual binaries have long orbital periods of several centuries or millennia and therefore have orbits which are uncertain or poorly known, they may be detected by indirect techniques, such as spectroscopy or astrometry. If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit each other. If components in binary star systems are close enough they can gravitationally distort their mutual outer stellar atmospheres. In some cases, these close binary systems can exchange mass, which may bring their evolution to stages that single stars cannot attain. Examples of binaries are Sirius, Cygnus X-1. Binary stars are common as the nuclei of many planetary nebulae, are the progenitors of both novae and type Ia supernovae; the term binary was first used in this context by Sir William Herschel in 1802, when he wrote: If, on the contrary, two stars should be situated near each other, at the same time so far insulated as not to be materially affected by the attractions of neighbouring stars, they will compose a separate system, remain united by the bond of their own mutual gravitation towards each other.
This should be called a real double star. By the modern definition, the term binary star is restricted to pairs of stars which revolve around a common center of mass. Binary stars which can be resolved with a telescope or interferometric methods are known as visual binaries. For most of the known visual binary stars one whole revolution has not been observed yet, they are observed to have travelled along a curved path or a partial arc; the more general term double star is used for pairs of stars which are seen to be close together in the sky. This distinction is made in languages other than English. Double stars may be binary systems or may be two stars that appear to be close together in the sky but have vastly different true distances from the Sun; the latter are termed optical optical pairs. Since the invention of the telescope, many pairs of double stars have been found. Early examples include Acrux. Mizar, in the Big Dipper, was observed to be double by Giovanni Battista Riccioli in 1650; the bright southern star Acrux, in the Southern Cross, was discovered to be double by Father Fontenay in 1685.
John Michell was the first to suggest that double stars might be physically attached to each other when he argued in 1767 that the probability that a double star was due to a chance alignment was small. William Herschel began observing double stars in 1779 and soon thereafter published catalogs of about 700 double stars. By 1803, he had observed changes in the relative positions in a number of double stars over the course of 25 years, concluded that they must be binary systems. Since this time, many more double stars have been measured; the Washington Double Star Catalog, a database of visual double stars compiled by the United States Naval Observatory, contains over 100,000 pairs of double stars, including optical doubles as well as binary stars. Orbits are known for only a few thousand of these double stars, most have not been ascertained to be either true binaries or optical double stars; this can be determined by observing the relative motion of the pairs. If the motion is part of an orbit, or if the stars have similar radial velocities and the difference in their proper motions is small compared to their common proper motion, the pair is physical.
One of the tasks that remains for visual observers of double stars is to obtain sufficient observations to prove or disprove gravitational connection. Binary stars are classified into four types accordi
Kepler-10b is the first confirmed terrestrial planet to have been discovered outside the Solar System by the Kepler Space Telescope. Discovered after several months of data collection during the course of the NASA-directed Kepler Mission, which aims to discover Earth-like planets crossing in front of their host stars, the planet's discovery was announced on January 10, 2011. Kepler-10b has a radius of 1.4 Earth radii. However, it lies close to its star, Kepler-10, as a result is too hot to support life as we know it, its existence was confirmed using measurements from the W. M. Keck Observatory in Hawaii. Kepler-10, the star that hosts Kepler-10b, is located 560 light-years from our solar system in the Draco constellation, it is the same size as the Sun, with an estimated age of 12 billion years. Planet Kepler-10b was the first planet to be discovered in the orbit of its star. For this, it was designated the star's b planet; the star, in turn, was named for the Kepler Mission, a NASA-led operation aimed at discovering terrestrial planets that transit, or cross in front of, their host stars with respect to Earth.
The planet's discovery was announced to the public on January 10, 2011. The transit method of discovering exoplanets relies upon monitoring the brightness of a star. If a planet is present and crosses the line of sight between Earth and the star, the star will dim at a regular interval by an amount that depends upon the radius of the transiting planet. In order to measure the mass of a planet, rule out other phenomena that can mimic the presence of a planet transiting a star, candidate transiting planets are followed up with the radial velocity method of detecting extrasolar planets. Kepler-10b's discovery was based on eight months of data collected with the Kepler telescope from May 2009 to January 2010; the planet's first transits were observed in July 2009. According to the collected data, Kepler-10 dimmed by one part in ten thousand every 0.83 days. Kepler-10 was the first star in the field of view of the Kepler telescope identified as capable of harboring a small transiting planet, was considered a high priority target for ground-based radial velocity observations intended to confirm the mass of Kepler-10b.
Radial velocity measurements with the Keck I telescope taken intermittently between August 2009 and August 2010 revealed a periodic Doppler shift in the spectrum of Kepler-10 consistent with a planet of the nature observed by Kepler, confirming the planet's existence and allowing its mass to be determined. The planet's discovery was announced to the public on January 10, 2011. On January 13, 2011, 3 days after the planet's discovery was announced, The Economist published an article suggesting "Vulcan" as an unofficial name for the planet, after both the hypothetical planet, the Roman god of the same name. In September 2011, the detection of secondary transit and phases were announced; this allowed to determine the albedo of the planet. This is the first terrestrial exoplanet with observed phases. Detection of phases was possible due to extreme day/night side temperature variations and the amount of starlight the planet receives due to its proximity to the host star. Kepler-10b's discovery excited astronomers, who hoped to use data about it to inquire into the formation and structure that terrestrial, Earth-size planets tend to have in common.
Geoff Marcy of the University of California at Berkeley said that the discovery was ranked "as among the most profound scientific discoveries in human history," and that the planet "will go into every textbook worldwide." Marcy described Kepler-10b as "a bridge between the gas giant planets we've been finding and the Earth itself." Diana Valencia at the University of Côte d'Azur in Nice, France considered the planet more of a "super-Mercury" than a super-Earth, granted its physical characteristics. Kepler-10b is most noted for its rocky surface, it has a diameter 1.4 times that of the Earth, a mass of 3.33±0.49 times that of Earth. The density of Kepler-10b is 5.8±0.8 g cm−3. It orbits its star, Kepler-10, in less than a day, at less than a twentieth of the distance from Mercury to the Sun, its surface temperature on the star lit side is 1833 K, as hot as a blast furnace and hot enough to melt iron. Though CoRoT-7b was discovered before Kepler-10b and has been claimed to be rocky, there is more room for other interpretations in the case of CoRoT-7b's composition than there is for Kepler-10b.
This is due to the much larger uncertainty in CoRoT-7b's mass, illustrated in the plot to the left. CoRoT-7b may be revealed to be a lava-ocean planet, whereas Kepler-10b must be predominantly made of rock or iron. In addition to showing the range of masses and radii consistent with the observations of each planet, the plot includes curves of compositions implied by certain masses and radii. Kepler-10b is tidally locked to its parent star and has extreme variations in temperature between day and night sides, it reflects about half of the starlight it receives. Kepler-10c Kepler Mission Kepler-4b, 5b, 6b, 7b, 8b, 9b, 78b List of extrasolar planet extremes Media related to Kepler-10 b at Wikimedia Commons NASA Kepler Mission: Kepler-10b YouTube: Narrated Animation on Kepler-10b
Cygnus is a northern constellation lying on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, it features a prominent asterism known as the Northern Cross. Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, it remains one of the 88 modern constellations. Cygnus contains Deneb -which is one of the brightest stars in the night sky and is the most distant first-magnitude star- as its "tail star" and one corner of the Summer Triangle, it has some notable X-ray sources and the giant stellar association of Cygnus OB2. Cygnus is known as the Northern Cross. One of the stars of this association, NML Cygni, is one of the largest stars known; the constellation is home to Cygnus X-1, a distant X-ray binary containing a supergiant and unseen massive companion, the first object held to be a black hole. Many star systems in Cygnus have known planets as a result of the Kepler Mission observing one patch of the sky, an area around Cygnus.
In addition, most of the eastern part of Cygnus is dominated by the Hercules–Corona Borealis Great Wall, a giant galaxy filament, the largest known structure in the observable universe, covering most of the northern sky. In Greek mythology, Cygnus has been identified with several different legendary swans. Zeus disguised himself as a swan to seduce Leda, Spartan king Tyndareus's wife, who gave birth to the Gemini, Helen of Troy, Clytemnestra; the Greeks associated this constellation with the tragic story of Phaethon, the son of Helios the sun god, who demanded to ride his father's sun chariot for a day. Phaethon, was unable to control the reins, forcing Zeus to destroy the chariot with a thunderbolt, causing it to plummet to the earth into the river Eridanus. According to the myth, Phaethon's brother, grieved bitterly and spent many days diving into the river to collect Phaethon's bones to give him a proper burial; the gods were so touched by Cygnus's devotion to his brother that they turned him into a swan and placed him among the stars.
In Ovid's Metamorphoses, there are three people named Cygnus, all of whom are transformed into swans. Alongside Cygnus, noted above, he mentions a boy from Tempe who commits suicide when Phyllius refuses to give him a tamed bull that he demands, but is transformed into a swan and flies away, he mentions a son of Neptune, an invulnerable warrior in the Trojan War, defeated by Achilles, but Neptune saves him by transforming him into a swan. Together with other avian constellations near the summer solstice, Vultur cadens and Aquila, Cygnus may be a significant part of the origin of the myth of the Stymphalian Birds, one of The Twelve Labours of Hercules. In Hinduism, the period of time or the Muhurta which lasts from 4:24 AM to 5:12 AM is called the "Brahma Muhurta" translating to "The moment of the Universe" and the Star system in correlation is the Cygnus constellation; this is a auspicious time to do any task or start the day. In Polynesia, Cygnus was recognized as a separate constellation. In Tonga it was called Tuula-lupe, in the Tuamotus it was called Fanui-tai.
Deneb was often given a name. The name Deneb comes from the Arabic name dhaneb, meaning "tail", from the phrase Dhanab ad-Dajājah, which means “the tail of the hen”. In New Zealand it was called Mara-tea, in the Society Islands it was called Pirae-tea or Taurua-i-te-haapa-raa-manu, in the Tuamotus it was called Fanui-raro. Beta Cygni was named in New Zealand. Gamma Cygni was called Fanui-runga in the Tuamotus. A large constellation, Cygnus is bordered by Cepheus to the north and east, Draco to the north and west, Lyra to the west, Vulpecula to the south, Pegasus to the southeast and Lacerta to the east; the three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is'Cyg'. The official constellation boundaries, as set by Eugène Delporte in 1930, are defined as a polygon of 28 segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 19h 07.3m and 22h 02.3m, while the declination coordinates are between 27.73° and 61.36°. Covering 804 square degrees and around 1.9% of the night sky, Cygnus ranks 16th of the 88 constellations in size.
Cygnus culminates at midnight on 29 June, is most visible in the evening from the early summer to mid-autumn in the Northern Hemisphere. Cygnus is depicted with Delta and Epsilon Cygni as its wings. Deneb, the brightest in the constellation is at its tail, Albireo as the tip of its beak. There are several asterisms in Cygnus. In the 17th-century German celestial cartographer Johann Bayer's star atlas the Uranometria, Alpha and Gamma Cygni form the pole of a cross, while Delta and Epsilon form the cross beam; the nova P Cygni was considered to be the body of Christ. Bayer catalogued many stars in the constellation, giving them the Bayer designations from Alpha to Omega and using lowercase Roman letters to g. John Flamsteed were dropped by Francis Baily. There are several bright stars in Cygnus. Alpha Cygni, called Deneb, is the brightest star in Cygnus, it is a white supergiant star of spectral type A2Iae that varies between magnitudes 1.21 and 1.29, one of the largest and most luminous A-class stars known.
It is located about 3200
Boötes is a constellation in the northern sky, located between 0° and +60° declination, 13 and 16 hours of right ascension on the celestial sphere. The name comes from the Greek Βοώτης, Boōtēs, meaning “herdsman” or “plowman”. One of the 48 constellations described by the 2nd-century astronomer Ptolemy, Boötes is now one of the 88 modern constellations, it contains the fourth-brightest star in the orange giant Arcturus. Epsilon Bootis, or Izar, is a colourful multiple star popular with amateur astronomers. Boötes is home to many other bright stars, including eight above the fourth magnitude and an additional 21 above the fifth magnitude, making a total of 29 stars visible to the naked eye. In ancient Babylon, the stars of Boötes were known as SHU. PA, they were depicted as the god Enlil, the leader of the Babylonian pantheon and special patron of farmers. Boötes may have been represented by the foreleg constellation in ancient Egypt. According to this interpretation, the constellation depicts the shape of an animal foreleg.
The name Boötes was first used by Homer in his Odyssey as a celestial reference point for navigation, described as "late-setting" or "slow to set", translated as the "Plowman". Whom Boötes is supposed to represent in Greek mythology is not clear. According to one version, he was a son of Demeter, twin brother of Plutus, a plowman who drove the oxen in the constellation Ursa Major; this is corroborated by the constellation's name, which itself means "ox-driver" or "herdsman." The ancient Greeks saw. This influenced the name's etymology, derived from the Greek for "noisy" or "ox-driver". Another myth associated with Boötes relates that he invented the plow and was memorialized for his ingenuity as a constellation. Another myth associated with Boötes by Hyginus is that of Icarius, schooled as a grape farmer and winemaker by Dionysus. Icarius made wine so strong that those who drank it appeared poisoned, which caused shepherds to avenge their poisoned friends by killing Icarius. Maera, Icarius' dog, brought his daughter Erigone to her father's body, whereupon both she and the dog committed suicide.
Zeus chose to honor all three by placing them in the sky as constellations: Icarius as Boötes, Erigone as Virgo, Maera as Canis Major or Canis Minor. Following another reading, the constellation is identified with Arcas and referred to as Arcas and Arcturus, son of Zeus and Callisto. Arcas was brought up by his maternal grandfather Lycaon, to whom one day Zeus had a meal. To verify that the guest was the king of the gods, Lycaon killed his grandson and prepared a meal made from his flesh. Zeus noticed and became angry, transforming Lycaon into a wolf and giving life back to his son. In the meantime Callisto had been transformed into a she-bear by Zeus's wife Hera, angry at Zeus's infidelity; this is corroborated by the Greek name for Boötes, which means "Bear Watcher". Callisto, in the form of a bear was killed by her son, out hunting. Zeus rescued her, taking her into the sky where she became Ursa Major, "the Great Bear". Arcturus, the name of the constellation's brightest star, comes from the Greek word meaning "guardian of the bear".
Sometimes Arcturus is depicted as leading the hunting dogs of nearby Canes Venatici and driving the bears of Ursa Major and Ursa Minor. Several former constellations were formed from stars now included in Boötes. Quadrans Muralis, the Quadrant, was a constellation created near Beta Boötis from faint stars, it was designated in 1795 by Jérôme Lalande, an astronomer who used a quadrant to perform detailed astronometric measurements. Lalande worked with others to predict the 1758 return of Halley's Comet. Quadrans Muralis was formed from the stars of eastern Boötes, western Hercules, Draco, it was called Le Mural by Jean Fortin in his 1795 Atlas Céleste. The constellation was quite faint, with its brightest stars reaching the 5th magnitude. Mons Maenalus, representing the Maenalus mountains, was created by Johannes Hevelius in 1687 at the foot of the constellation's figure; the mountain was named for the son of Maenalus. The mountain, one of Diana's hunting grounds, was holy to Pan; the stars of Boötes were incorporated into many different Chinese constellations.
Arcturus was part of the most prominent of these, variously designated as the celestial king's throne or the Blue Dragon's horn. Arcturus was given such importance in Chinese celestial mythology because of its status marking the beginning of the lunar calendar, as well as its status as the brightest star in the northern night sky. Two constellations flanked Daijiao: Yousheti to Zuosheti to the left. Zuosheti was formed from modern Zeta, Pi Boötis, while Yousheti was formed from modern Eta and Upsilon Boötis. Dixi, the Emperor's ceremonial banquet mat, was north of Arcturus, consisting of the stars 12, 11, 9 Boötis. Another northern constellation was Qigong, the Seven Dukes, which straddled the Boötes-Hercules border, it included either Delta Boötis or Beta Boötis as its terminus. The other Chinese constellations made up of the stars of Boötes existed in the modern constellation's north. Tianqiang, the spear, was formed from Iota and Theta Boötis. There were two
Hercules is a constellation named after Hercules, the Roman mythological hero adapted from the Greek hero Heracles. Hercules was one of the 40 constellations listed by the 3rd century astronomer Ptolemy, it remains one of the 88 modern constellations today, it is the second largest of the modern constellations. Hercules is bordered by Draco to the north. Covering 1225.1 square degrees and 2.970% of the night sky, it ranks 5th among the 88 constellations in size. 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 the equatorial coordinate system, epoch 2000, the right ascension coordinates of these borders lie between 16h 00m 26.64s and 18h 57m 49.50s, while the declination coordinates are between +3.67° and +51.32°. 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 Sun's motion with respect to the Local Standard of Rest. This is located within the constellation of Hercules, around coordinates Right Ascension 18h 00m and Declination 30°; the north pole of the supergalactic coordinate system is located within this constellation at Right Ascension 18h 55m 01s and Declination +15° 42′ 32″. Hercules has no second magnitude stars. However, it does have several stars above magnitude 4. Alpha Herculis, traditionally called Rasalgethi, is a triple star system resolvable in small amateur telescopes, 359 light-years from Earth; the primary is an irregular variable star. It has a diameter of 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 kneeler's head". Beta Herculis called Kornephoros, is the brightest star in Hercules, it is a yellow giant of 148 light-years from Earth. Its traditional name means "club-bearer".
Deltoide 5512 is a double star divisible in small amateur telescopes. The primary is a blue-white star of magnitude 3.1, is 78 light-years from Earth. The optical companion is of magnitude 8.2. Gamma Herculis is a double star divisible in small amateur telescopes; the primary is a white giant of 195 light-years from Earth. The optical companion separated, is 10th magnitude. Zeta Herculis is a binary star, becoming divisible in medium-aperture amateur telescopes, as the components widen to their peak in 2025; the system, 35 light-years from Earth, has a period of 34.5 years. The primary is a yellow-tinged star of magnitude 2.9 and the secondary is an orange star of magnitude 5.7. There are several dimmer variable stars in Hercules. 30 Herculis called g Herculis, is a semiregular red giant with a period of 3 months. 361 light-years from Earth, it has a minimum magnitude of 6.3 and a maximum magnitude of 4.3. 68 Herculis called u Herculis, is a Beta Lyrae-type eclipsing binary star. 865 light-years from Earth, it has a period of 2 days.
Hercules is home to many double stars and binary stars. Kappa Herculis is a double star divisible in small amateur telescopes; the primary is a yellow giant of 388 light-years from Earth. Rho Herculis is a binary star 402 light-years from Earth, divisible in small amateur telescopes. Both components are blue-green giant stars. 95 Herculis is a binary star divisible in 470 light-years from Earth. The primary is a silvery giant of magnitude 4.9, the secondary is an old, reddish giant star of magnitude 5.2. The star HD164669 near the primary may be an optical double. 100 Herculis is a double star divisible in small amateur telescopes. Both components are magnitude 5.8 blue-white stars. Mu Herculis is 27.4 light-years from Earth. The solar apex, i.e. the point on the sky which marks the direction that the Sun is moving in its orbit around the center of the Milky Way, is located within Hercules, close to Vega in neighboring Lyra. Fifteen stars in Hercules are known to be orbited by extrasolar planets. 14 Herculis has two planets.
The planet 14 Herculis b had the longest widest orbit at the time of discovery. The planet 14 Herculis c orbits much further out with low eccentricity. HD 149026 is one of the most prominent and studied. HD 154345 has the planet HD 154345 a long period and wide orbit. HD 164922 has the first long period Saturn-like planet discovered; the mass is 0.36 MJ and semimajor axis of 2.11 AU. HD 147506 has the most massive transiting planet HAT-P-2b at the time of discovery; the mass is 8.65 MJ. HD 155358 has two planets around the lowest metallicity planet-harboring star. Both planets orbit in mild eccentricities. GSC 03089-00929 has a short transiting planet TrES-3; the period was 31 hours and undergoing orbital decay. Gliese 649 has a saturnian planet around the red dwarf star. HD 156668 has a 4.15 Earth mass planet. HD 164595, one known planet, HD 164595 b. AT2018cow, a large astronomical explosion detected on 16 June 2018; as of 22 June 2018, this astronomical event has generated a large amount of interest among astronomers throughout th