Lyra is a small constellation. It is one of 48 listed by the 2nd century astronomer Ptolemy, is one of the 88 constellations recognized by the International Astronomical Union. Lyra was represented on star maps as a vulture or an eagle carrying a lyre, hence is sometimes referred to as Vultur Cadens or Aquila Cadens, respectively. Beginning at the north, Lyra is bordered by Draco, Hercules and Cygnus. Lyra is visible from the northern hemisphere from spring through autumn, nearly overhead, in temperate latitudes, during the summer months. From the southern hemisphere, it is visible low in the northern sky during the winter months. Vega, Lyra's brightest star, is one of the brightest stars in the night sky, forms a corner of the famed Summer Triangle asterism. Beta Lyrae is the prototype of a class of stars known as Beta Lyrae variables; these binary stars are so close to each other that they become egg-shaped and material flows from one to the other. Epsilon Lyrae, known informally as the Double Double, is a complex multiple star system.
Lyra hosts the Ring Nebula, the second-discovered and best-known planetary nebula. In Greek mythology, Lyra represents the lyre of Orpheus. Made by Hermes from a tortoise shell, given to Apollo as a bargain, it was said to be the first lyre produced. Orpheus's music was said to be so great that inanimate objects such as trees and rocks could be charmed. Joining Jason and the Argonauts, his music was able to quell the voices of the dangerous Sirens, who sang tempting songs to the Argonauts. At one point, Orpheus married a nymph. While fleeing from an attack by Aristaeus, she stepped on a snake. To reclaim her, Orpheus entered the Underworld. Hades relented and let Orpheus bring Eurydice back, on the condition that he never once look back until outside. Near the end, Orpheus faltered and looked back, causing Eurydice to be left in the Underworld forever. Orpheus spent the rest of his life strumming his lyre while wandering aimlessly through the land, rejecting all marriage offers from women. There are two competing myths relating to the death of Orpheus.
According to Eratosthenes, Orpheus failed to make a necessary sacrifice to Dionysus due to his regard for Apollo as the supreme deity instead. Dionysus sent his followers to rip Orpheus apart. Ovid tells a rather different story, saying that women, in retribution for Orpheus's rejection of marriage offers, ganged up and threw stones and spears. At first, his music charmed them as well, but their numbers and clamor overwhelmed his music and he was hit by the spears. Both myths state that his lyre was placed in the sky by Zeus, Orpheus' bones buried by the muses. Vega and its surrounding stars are treated as a constellation in other cultures; the area corresponding to Lyra was seen by the Arabs as a vulture or an eagle carrying a lyre, either enclosed in its wings, or in its beak. In Wales, Lyra is known as King Arthur's Harp, King David's harp; the Persian Hafiz called it the Lyre of Zurah. It has been called the Manger of Praesepe Salvatoris. In Australian Aboriginal astronomy, Lyra is known by the Boorong people in Victoria as the Malleefowl constellation.
Lyra was worshipped as an animal deity. Lyra is bordered by Vulpecula to the south, Hercules to the east, Draco to the north, Cygnus to the west. Covering 286.5 square degrees, it ranks 52nd of the 88 modern constellations in size. It appears prominently in the northern sky during the Northern Hemisphere's summer, the whole constellation is visible for at least part of the year to observers north of latitude 42°S, its main asterism consists of six stars, 73 stars in total are brighter than magnitude 6.5. The constellation's boundaries, as set by Eugène Delporte in 1930, are defined by a 17-sided polygon. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 18h 14m and 19h 28m, while the declination coordinates are between +25.66° and +47.71°. The International Astronomical Union adopted the three-letter abbreviation "Lyr" for the constellation in 1922. German cartographer Johann Bayer used the Greek letters alpha through nu to label the most prominent stars in the constellation.
Flamsteed observed and labelled two stars each as delta, zeta and nu. He added pi and rho, not using xi and omicron as Bayer used hese letters to denote Cygnus and Hercules on his map; the brightest and far the most well-known star in the constellation is Vega, a main-sequence star of spectral type A0Va. Only 7.7 parsecs distant, is a Delta Scuti variable, varying between magnitudes −0.02 and 0.07 over 0.2 days. On average, it is the second-brightest star of a northern hemisphere and the fifth-brightest star in all, surpassed only by Arcturus, Alpha Centauri and Sirius. Vega was the pole star in the year 12,000 BCE, will again become the pole star around 14,000 CE. Vega is one of the most-magnificent of all stars, has been called "arguably the next most important star in the sky after the Sun". Vega was the first star other than the Sun to be photographed, as well as the first to have a clear spectrum recorded, showing absorption lines for the first time; the star was the first single main-sequence star other than the Sun to be known to emit X-rays, is surrounded by a circumstellar debris disk, similar to the Kuiper Belt.
Vega forms one corner of the famous Summer Triangle asterism. Vega forms one vertex of a much s
HD 189733 b
HD 189733 b is an extrasolar planet 63 light-years away from the Solar System in the constellation of Vulpecula. The planet was discovered orbiting the star HD 189733 A on October 5, 2005, when astronomers in France observed the planet transiting across the face of the star. With a mass 13% higher than that of Jupiter, HD 189733 b orbits its host star once every 2.2 days at an orbital speed of 152.5 kilometres per second, making it a hot Jupiter with poor prospects for extraterrestrial life. Being the closest transiting hot Jupiter to Earth, HD 189733 b is a subject for extensive atmospheric examination; the atmosphere of HD 189733b has been extensively studied through high- and low-resolution instruments, both from ground and space. HD 189733 b was the first extrasolar planet for which a thermal map was constructed to be detected through polarimetry, to have its overall color determined, to have a transit detected in X-ray spectrum and to have carbon dioxide detected in its atmosphere. In July 2014, NASA announced finding dry atmospheres on three exoplanets orbiting Sun-like stars.
On October 6, 2005, a team of astronomers announced the discovery of transiting planet HD 189733 b. The planet was detected using Doppler spectroscopy. Real-time radial velocity measurements detected the Rossiter–McLaughlin effect caused by the planet passing in front of its star before photometric measurements confirmed that the planet was transiting. In 2006, a team led by Drake Deming announced a detection of strong infrared thermal emission from the transiting exoplanet planet HD 189733 b, by measuring the flux decrement during its prominent secondary eclipse; the mass of the planet is estimated to be 13% larger than Jupiter's, with the planet completing an orbit around its host star every 2.2 days and an orbital speed of 152.5 km/s. On February 21, 2007, NASA released news that the Spitzer Space Telescope had measured detailed spectra from both HD 189733 b and HD 209458 b; the release came with the public release of a new issue of Nature containing the first publication on the spectroscopic observation of the other exoplanet, HD 209458 b.
A paper was published by the Astrophysical Journal Letters. The spectroscopic observations of HD 189733 b were led by Carl Grillmair of NASA's Spitzer Science Center. In 2008, a team of astrophysicists appeared to have detected and monitored the planet's visible light using polarimetry, which would have been the first such success; this result seemed to be confirmed and refined by the same team in 2011. They found that the planet albedo is larger in blue light than in the red, most due to Rayleigh scattering and molecular absorption in the red; the blue color of the planet was subsequently confirmed in 2013, which would have made HD 189733 the first planet to have its overall color determined by two different techniques. These measurements in polarized light have since been disputed by two separate teams using more sensitive polarimeters, with upper limits of the polarimetric signal provided therein; the blueness of the planet may be the result of Rayleigh scattering. In mid January 2008, spectral observation during the planet's transit using that model found that if molecular hydrogen exists, it would have an atmospheric pressure of 410 ± 30 mbar of 0.1564 solar radii.
The Mie approximation model found that there is a possible condensate in its atmosphere, magnesium silicate with a particle size of 10−2 to 10−1 μm. Using both models, the planet's temperature would be between 1340 and 1540 K; the Rayleigh effect is confirmed in other models, by the apparent lack of a cooler, shaded stratosphere below its outer atmosphere. In the visible region of the spectrum, thanks to their high absorption cross sections, atomic sodium and potassium can be investigated. For example, using high-resolution UVES spectrograph on VLT, sodium has been detected on this atmosphere and further physical characteristics of the atmosphere such as temperature has been investigated. In July 2013, NASA reported the first observations of planet transit studied in X-ray spectrum, it was found. In March 2010, transit observations using HI Lyman-alpha found that this planet is evaporating at a rate of 1-100 gigagrams per second; this indication was found by detecting the extended exosphere of atomic hydrogen.
HD 189733 b is the second planet after HD 209458 b for which atmospheric evaporation has been detected. This planet exhibits one of the largest photometric transit depth of extrasolar planets so far observed 3%; the apparent longitude of ascending node of its orbit is 16 degrees +/- 8 away from north-south in our sky. It and HD 209458 b were the first two planets; the parent stars of these two planets are the brightest transiting-planet host stars, so these planets will continue to receive the most attention by astronomers. Like most hot Jupiters, this planet is thought to be tidally locked to its parent star, meaning it has a permanent day and night; the planet is not oblate, has neither satellites with greater than 0.8 the radius of Earth nor a ring system like that of Saturn. The international team under the direction of Svetlana Berdyugina of Zurich University of Technology, using the Swedish 60-centimeter telescope KVA, located in Spain, was able to directly see the polarized light reflected from the planet.
The polarization indicates that the scattering atmosphere is larger than the opaque body of the planet seen during transits. The atmos
Altair designated α Aquilae, is the brightest star in the constellation of Aquila and the twelfth brightest star in the night sky. It is in the G-cloud—a nearby interstellar cloud, an accumulation of gas and dust. Altair is an A-type main sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the Summer Triangle asterism. It is one of the closest stars visible to the naked eye. Altair rotates with a velocity at the equator of 286 km/s; this is a significant fraction of the star's estimated breakup speed of 400 km/s. A study with the Palomar Testbed Interferometer revealed that Altair is not spherical, but is flattened at the poles due to its high rate of rotation. Other interferometric studies with multiple telescopes, operating in the infrared, have imaged and confirmed this phenomenon. Α Aquilae is the star's Bayer designation. The traditional name Altair has been used since medieval times, it is an abbreviation of al-nesr al-ṭā' ir. In 2016, the International Astronomical Union organized a Working Group on Star Names to catalog and standardize proper names for stars.
The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Altair for this star. It is now so entered in the IAU Catalog of Star Names. Along with β Aquilae and γ Aquilae, Altair forms the well-known line of stars sometimes referred to as the Family of Aquila or Shaft of Aquila. Altair is a type-A main sequence star with about 1.8 times the mass of the Sun and 11 times its luminosity. Altair rotates with a rotational period of about 9 hours, its rapid rotation forces Altair to be oblate. Satellite measurements made in 1999 with the Wide Field Infrared Explorer showed that the brightness of Altair fluctuates varying by just a few thousandths of a magnitude with several different periods less than 2 hours; as a result, it was identified in 2005 as a Delta Scuti variable star. Its light curve can be approximated by adding together a number of sine waves, with periods that range between 0.8 and 1.5 hours. It is a weak source of coronal X-ray emission, with the most active sources of emission being located near the star's equator.
This activity may be due to convection cells forming at the cooler equator. The angular diameter of Altair was measured interferometrically by R. Hanbury Brown and his co-workers at Narrabri Observatory in the 1960s, they found a diameter of 3 milliarcseconds. Although Hanbury Brown et al. realized that Altair would be rotationally flattened, they had insufficient data to experimentally observe its oblateness. Altair was observed to be flattened by infrared interferometric measurements made by the Palomar Testbed Interferometer in 1999 and 2000; this work was published by G. T. van Belle, David R. Ciardi and their co-authors in 2001. Theory predicts that, owing to Altair's rapid rotation, its surface gravity and effective temperature should be lower at the equator, making the equator less luminous than the poles; this phenomenon, known as gravity darkening or the von Zeipel effect, was confirmed for Altair by measurements made by the Navy Prototype Optical Interferometer in 2001, analyzed by Ohishi et al. and Peterson et al..
A. Domiciano de Souza et al. verified gravity darkening using the measurements made by the Palomar and Navy interferometers, together with new measurements made by the VINCI instrument at the VLTI. Altair is one of the few stars. In 2006 and 2007, J. D. Monnier and his coworkers produced an image of Altair's surface from 2006 infrared observations made with the MIRC instrument on the CHARA array interferometer; the false-color image was published in 2007. The equatorial radius of the star was estimated to be 2.03 solar radii, the polar radius 1.63 solar radii—a 25% increase of the stellar radius from pole to equator. The polar axis is inclined by about 60° to the line of sight from the Earth; the term Al Nesr Al Tair appeared in Al Achsasi al Mouakket's catalogue, translated into Latin as Vultur Volans. This name was applied by the Arabs to the asterism of Altair, β Aquilae, γ Aquilae and goes back to the ancient Babylonians and Sumerians, who called Altair "the eagle star"; the spelling Atair has been used.
Medieval astrolabes of England and Western Europe depicted Vega as birds. The Koori people of Victoria knew Altair as Bunjil, the wedge-tailed eagle, β and γ Aquilae are his two wives the black swans; the people of the Murray River knew the star as Totyerguil. The Murray River was formed when Totyerguil the hunter speared Otjout, a giant Murray cod, when wounded, churned a channel across southern Australia before entering the sky as the constellation Delphinus. In Chinese, the asterism consisting of Altair, β Aquilae, γ Aquilae is known as Hé Gǔ; the Chinese name for Altair is thus Hé Gǔ èr. However, Altair is better known by its other names: Qiān Niú Xīng or Niú Láng Xīng, translated as the cowherd star; these names are an allusion to a love story, The Cowherd and the Weaver
The apparent magnitude of an astronomical object is a number, a measure of its brightness as seen by an observer on Earth. The magnitude scale is logarithmic. A difference of 1 in magnitude corresponds to a change in brightness by a factor of 5√100, or about 2.512. The brighter an object appears, the lower its magnitude value, with the brightest astronomical objects having negative apparent magnitudes: for example Sirius at −1.46. The measurement of apparent magnitudes or brightnesses of celestial objects is known as photometry. Apparent magnitudes are used to quantify the brightness of sources at ultraviolet and infrared wavelengths. An apparent magnitude is measured in a specific passband corresponding to some photometric system such as the UBV system. In standard astronomical notation, an apparent magnitude in the V filter band would be denoted either as mV or simply as V, as in "mV = 15" or "V = 15" to describe a 15th-magnitude object; the scale used to indicate magnitude originates in the Hellenistic practice of dividing stars visible to the naked eye into six magnitudes.
The brightest stars in the night sky were said to be of first magnitude, whereas the faintest were of sixth magnitude, the limit of human visual perception. Each grade of magnitude was considered twice the brightness of the following grade, although that ratio was subjective as no photodetectors existed; this rather crude scale for the brightness of stars was popularized by Ptolemy in his Almagest and is believed to have originated with Hipparchus. In 1856, Norman Robert Pogson formalized the system by defining a first magnitude star as a star, 100 times as bright as a sixth-magnitude star, thereby establishing the logarithmic scale still in use today; this implies that a star of magnitude m is about 2.512 times as bright as a star of magnitude m + 1. This figure, the fifth root of 100, became known as Pogson's Ratio; the zero point of Pogson's scale was defined by assigning Polaris a magnitude of 2. Astronomers discovered that Polaris is variable, so they switched to Vega as the standard reference star, assigning the brightness of Vega as the definition of zero magnitude at any specified wavelength.
Apart from small corrections, the brightness of Vega still serves as the definition of zero magnitude for visible and near infrared wavelengths, where its spectral energy distribution approximates that of a black body for a temperature of 11000 K. However, with the advent of infrared astronomy it was revealed that Vega's radiation includes an Infrared excess due to a circumstellar disk consisting of dust at warm temperatures. At shorter wavelengths, there is negligible emission from dust at these temperatures. However, in order to properly extend the magnitude scale further into the infrared, this peculiarity of Vega should not affect the definition of the magnitude scale. Therefore, the magnitude scale was extrapolated to all wavelengths on the basis of the black-body radiation curve for an ideal stellar surface at 11000 K uncontaminated by circumstellar radiation. On this basis the spectral irradiance for the zero magnitude point, as a function of wavelength, can be computed. Small deviations are specified between systems using measurement apparatuses developed independently so that data obtained by different astronomers can be properly compared, but of greater practical importance is the definition of magnitude not at a single wavelength but applying to the response of standard spectral filters used in photometry over various wavelength bands.
With the modern magnitude systems, brightness over a wide range is specified according to the logarithmic definition detailed below, using this zero reference. In practice such apparent magnitudes do not exceed 30; the brightness of Vega is exceeded by four stars in the night sky at visible wavelengths as well as the bright planets Venus and Jupiter, these must be described by negative magnitudes. For example, the brightest star of the celestial sphere, has an apparent magnitude of −1.4 in the visible. Negative magnitudes for other bright astronomical objects can be found in the table below. Astronomers have developed other photometric zeropoint systems as alternatives to the Vega system; the most used is the AB magnitude system, in which photometric zeropoints are based on a hypothetical reference spectrum having constant flux per unit frequency interval, rather than using a stellar spectrum or blackbody curve as the reference. The AB magnitude zeropoint is defined such that an object's AB and Vega-based magnitudes will be equal in the V filter band.
As the amount of light received by a telescope is reduced by transmission through the Earth's atmosphere, any measurement of apparent magnitude is corrected for what it would have been as seen from above the atmosphere. The dimmer an object appears, the higher the numerical value given to its apparent magnitude, with a difference of 5 magnitudes corresponding to a brightness factor of 100. Therefore, the apparent magnitude m, in the spectral band x, would be given by m x = − 5 log 100 , more expressed in terms of common logarithms as m x
A telescope is an optical instrument that makes distant objects appear magnified by using an arrangement of lenses or curved mirrors and lenses, or various devices used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. The first known practical telescopes were refracting telescopes invented in the Netherlands at the beginning of the 17th century, by using glass lenses, they were used for both terrestrial applications and astronomy. The reflecting telescope, which uses mirrors to collect and focus light, was invented within a few decades of the first refracting telescope. In the 20th century, many new types of telescopes were invented, including radio telescopes in the 1930s and infrared telescopes in the 1960s; the word telescope now refers to a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, in some cases other types of detectors. The word telescope was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo Galilei's instruments presented at a banquet at the Accademia dei Lincei.
In the Starry Messenger, Galileo had used the term perspicillum. The earliest existing record of a telescope was a 1608 patent submitted to the government in the Netherlands by Middelburg spectacle maker Hans Lippershey for a refracting telescope; the actual inventor is unknown but word of it spread through Europe. Galileo heard about it and, in 1609, built his own version, made his telescopic observations of celestial objects; 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 and several attempts to build reflecting telescopes. 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 achromatic lens in 1733 corrected color aberrations present in the simple lens and enabled the construction of shorter, more functional refracting telescopes.
Reflecting telescopes, though not limited by the color problems seen in refractors, were hampered by the use of fast tarnishing speculum metal mirrors employed during the 18th and early 19th century—a problem alleviated by the introduction of silver coated glass mirrors in 1857, aluminized mirrors in 1932. The maximum physical size limit for refracting telescopes is about 1 meter, dictating that the vast majority of large optical researching telescopes built since the turn of the 20th century have been reflectors; the largest reflecting telescopes have objectives larger than 10 m, work is underway on several 30-40m designs. The 20th century 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 a large variety of complex astronomical instruments have been developed; the name "telescope" covers a wide range of instruments. Most detect electromagnetic radiation, but there are major differences in how astronomers must go about collecting light in different frequency bands.
Telescopes may be classified by the wavelengths of light they detect: X-ray telescopes, using shorter wavelengths than ultraviolet light Ultraviolet telescopes, using shorter wavelengths than visible light Optical telescopes, using visible light Infrared telescopes, using longer wavelengths than visible light Submillimetre telescopes, using longer wavelengths than infrared light Fresnel Imager, an optical lens technology X-ray optics, optics for certain X-ray wavelengthsAs wavelengths become longer, it becomes easier to use antenna technology to interact with electromagnetic radiation. The near-infrared can be collected much like visible light, however in the far-infrared and submillimetre range, telescopes can operate more like a radio telescope. For example, the James Clerk Maxwell Telescope observes from wavelengths from 3 μm to 2000 μm, but uses a parabolic aluminum antenna. On the other hand, the Spitzer Space Telescope, observing from about 3 μm to 180 μm uses a mirror. Using reflecting optics, the Hubble Space Telescope with Wide Field Camera 3 can observe in the frequency range from about 0.2 μm to 1.7 μm.
With photons of the shorter wavelengths, with the higher frequencies, glancing-incident optics, rather than reflecting optics are used. Telescopes such as TRACE and SOHO use special mirrors to reflect Extreme ultraviolet, producing higher resolution and brighter images than are otherwise possible. A larger aperture does not just mean that more light is collected, it enables a finer angular resolution. Telescopes may be classified by location: ground telescope, space telescope, or flying telescope, they may be classified by whether they are operated by professional astronomers or amateur astronomers. A vehicle or permanent campus containing one or more telescopes or other instruments is called an observatory. An optical telescope gathers and focuses light from the visible part of the electromagnetic spectrum. Optical telescopes increase the apparent angular size of distant objects as well as their apparent brightness. In order for the image to be observed, photographed and sent to a computer, telescopes work by employing one or
Jocelyn Bell Burnell
Dame Susan Jocelyn Bell Burnell is an astrophysicist from Northern Ireland who, as a postgraduate student, co-discovered the first radio pulsars in 1967. She was credited with "one of the most significant scientific achievements of the 20th century"; the discovery was recognised by the award of the 1974 Nobel Prize in Physics, but despite the fact that she was the first to observe the pulsars, Bell was not one of the recipients of the prize. The paper announcing the discovery of pulsars had five authors. Bell's thesis supervisor Antony Hewish was listed first, Bell second. Hewish was awarded the Nobel Prize, along with the astronomer Martin Ryle. Many prominent astronomers criticised Bell's omission, including Sir Fred Hoyle. In 1977, Bell Burnell played down this controversy, saying, "I believe it would demean Nobel Prizes if they were awarded to research students, except in exceptional cases, I do not believe this is one of them." The Royal Swedish Academy of Sciences, in its press release announcing the 1974 Nobel Prize in Physics, cited Ryle and Hewish for their pioneering work in radio-astrophysics, with particular mention of Ryle's work on aperture-synthesis technique, Hewish's decisive role in the discovery of pulsars.
Bell served as president of the Royal Astronomical Society from 2002 to 2004, as president of the Institute of Physics from October 2008 until October 2010, as interim president of the Institute following the death of her successor, Marshall Stoneham, in early 2011. In 2018, she was awarded the Special Breakthrough Prize in Fundamental Physics, she donated the whole of the £2.3 million prize money to help female and refugee students become physics researchers. Jocelyn Bell was born in Northern Ireland, to M. Allison and G. Philip Bell, her father was an architect who had helped design the Armagh Planetarium, during visits she was encouraged by the staff to pursue astronomy professionally. Young Jocelyn discovered her father's books on astronomy, she grew up in Lurgan and attended the Preparatory Department of Lurgan College from 1948 to 1956, where she, like the other girls, was not permitted to study science until her parents protested against the school's policy. The girls' curriculum had included such subjects as cooking and cross-stitching rather than science.
She failed the eleven-plus exam and her parents sent her to The Mount School, a Quaker girls' boarding school in York, England. There she was favourably impressed by her physics teacher, Mr Tillott, stated: You do not have to learn lots and lots... of facts. He was a good teacher and showed me how easy physics was. Bell Burnell was the subject of the first part of the BBC Four three-part series Beautiful Minds, directed by Jacqui Farnham, she graduated from the University of Glasgow with a Bachelor of Science degree in Natural Philosophy, with honours, in 1965 and obtained a PhD degree from the University of Cambridge in 1969. At Cambridge, she attended New Hall and worked with Hewish and others to construct the Interplanetary Scintillation Array to study quasars, discovered. In July 1967, she detected a bit of "scruff" on her chart-recorder papers that tracked across the sky with the stars, she established that the signal was pulsing with great regularity, at a rate of about one pulse every one and a third seconds.
Temporarily dubbed "Little Green Man 1" the source was identified after several years as a rotating neutron star. This was documented by the BBC Horizon series, she worked at the University of Southampton between 1968 and 1973, University College London from 1974 to 82 and the Royal Observatory, Edinburgh. From 1973 to 1987 she was a tutor, consultant and lecturer for the Open University. In 1986, she became the project manager for the James Clerk Maxwell Telescope on Hawaii, she was Professor of Physics at the Open University from 1991 to 2001. She was a visiting professor at Princeton University in the United States and Dean of Science at the University of Bath, President of the Royal Astronomical Society between 2002 and 2004. Bell Burnell is Visiting Professor of Astrophysics at the University of Oxford, a Fellow of Mansfield College, she was President of the Institute of Physics between 2008 and 2010. In February 2018 she was appointed Chancellor of the University of Dundee. In 2018, Bell Burnell visited Parkes, NSW, to deliver the keynote John Bolton lecture at the CWAS AstroFest event.
In 2018, she was awarded the Special Breakthrough Prize in Fundamental Physics, worth three million dollars, for her discovery of radio pulsars. The Special Prize, in contrast to the regular annual prize, is not restricted to recent discoveries, she donated all of the money "to fund women, under-represented ethnic minority and refugee students to become physics researchers", the funds to be administered by the Institute of Physics. That Bell did not receive recognition in the 1974 Nobel Prize in Physics has been a point of controversy since, she helped build the Interplanetary Scintillation Array over two years and noticed the anomaly, sometimes reviewing as much as 96 feet of paper data per night. Bell claimed that she had to be persistent in reporting the anomaly in the face of scepticism from Hewish, insistent that it was due to interference and man-made, she spoke of meetings held by Ryle to which she was not invited. In 1977, she commented on the issue: First, demarcation disputes between supervisor and student are always difficult impossible to resolve.
Common brushtail possum
The common brushtail possum is a nocturnal, semi-arboreal marsupial of the family Phalangeridae, it is native to Australia, the second largest of the possums. Like most possums, the common brushtail possum is nocturnal, it is a folivore, but has been known to eat small mammals such as rats. In most Australian habitats, leaves of eucalyptus are a significant part of the diet but the sole item eaten; the tail is naked on its lower underside. There are four colour variations: silver-grey, brown and gold, it is the Australian marsupial most seen by city-dwellers, as it is one of few that thrives in cities as well as a wide range of natural and human-modified environments. Around human habitations, common brushtails are inventive and determined foragers with a liking for fruit trees, vegetable gardens, kitchen raids; the common brushtail possum was introduced to New Zealand in the 1850s to establish a fur industry, but in the mild subtropical climate of New Zealand, with few to no natural predators, it thrived to the extent that it became a major agricultural and conservation pest.
The common brushtail possum has pointed ears. It has a bushy tail, adapted to grasping branches, prehensile at the end with a hairless ventral patch, its forefeet have sharp claws and the first toe of each hind foot is clawless but has a strong grasp. The possum grooms itself with the fourth toes which are fused together, it has a woolly pelage that varies in colour depending on the subspecies. Colour patterns tend to be silver-gray, black, red or cream; the ventral areas are lighter and the tail is brown or black. The muzzle is marked with dark patches; the common brushtail possum has a body length of 32 -- 58 cm with a tail length of 24 -- 40 cm. It weighs 1.2-4.5 kg. Males are larger than females. In addition, the coat of the male tends to be reddish at the shoulders; as with most marsupials, the female brushtail possum has a well-developed pouch. The chest of both sexes has a scent gland that emits a reddish secretion which stains that fur around it, it marks its territory with these secretions.
The common brushtail possum is the most widespread marsupial of Australia. It is found throughout the eastern and northern parts of the continent, as well as some western regions, Tasmania and a number of offshore islands, such as Kangaroo Island and Barrow Island, it is widespread in New Zealand since its introduction in 1840. The common brushtail possum can be found in a variety of habitats, such as forests, semiarid areas and cultivated or urban areas, it is a forest inhabiting species, however it is found in treeless areas. In New Zealand, possums favour broadleaf-podocarp near farmland pastures. In southern beech forests and pine plantations, possums are less common. Overall, brushtail possums are more densely populated in New Zealand than in their native Australia; this may be because Australia has more predators. In Australia, brushtail possums are threatened by humans, tiger quolls, foxes, goannas, carpet snakes and powerful owls. In New Zealand, brushtail possums are threatened only by cats.
The IUCN highlight the population trend in Australia as decreasing. The common brushtail possum can adapt to numerous kinds of vegetation, it prefers Eucalyptus leaves but will eat flowers, shoots and seeds. It may consume animal matter such as insects, birds' eggs and chicks, other small vertebrates. Brushtail possums may eat three or four different plant species during a foraging trip, unlike some other arboreal marsupials, such as the koala and the greater glider, which focus on single species; the brushtail possum's rounded molars cannot cut Eucalyptus leaves as finely as more specialised feeders. They are more adapted to crushing their food which enables them to chew fruit or herbs more effectively; the brushtail possums' caecum lacks internal ridges and cannot separate coarse and fine particles as efficiently as some other arboreal marsupials. The brushtail possum cannot rely on Eucalyptus alone to provide sufficient nitrogen, its more generalised and mixed diet, does provide adequate nitrogen.
The common brushtail possum is arboreal and nocturnal. It has a solitary lifestyle, individuals keep their distance with scent markings and vocalisations. Brushtail possums make their dens in natural places like tree hollows and caves but will use spaces in the roofs of houses. While they sometimes share dens, brushtails sleep in separate dens. Individuals from New Zealand use many more den sites than those from Australia. Brushtail possums compete with each other and other animals for den spaces and this contributes to their mortality; this is another reason why brushtail possum population densities are smaller in Australia than in New Zealand. Brushtail possums are not aggressive towards each other and just stare with erect ears. Brushtail possums vocalise with clicks, hisses, alarm chatters, guttural coughs and screeching; the common brushtail possum can breed at any time of the year, but breeding tends to peak in spring, from September to November, in autumn, from March to May, in some areas.
Mating is random. In one Queensland population, it takes the males one month of consorting with females before they can mate with them. Females have a gestation period of 16 -- 18 days. A newborn brushtai