Pyxis
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{{#invoke:Infobox|infobox}}Template:Template other{{#invoke:Check for unknown parameters|check|unknown=Template:Main other|preview=Page using Template:Infobox constellation with unknown parameter "_VALUE_"|ignoreblank=y| name | abbreviation | genitive | pronounce | symbolism | RA | dec | family | quadrant | areatotal | arearank | numbermainstars | numberbfstars | numberstarsplanets | numberbrightstars | numbernearbystars | brighteststarname | starmagnitude | neareststarname | stardistancely | stardistancepc | stardistance | numbermessierobjects | meteorshowers | bordering | latmax | latmin | month | notes }} PyxisTemplate:Efn is a small and faint constellation in the southern sky. Abbreviated from Pyxis Nautica, its name is Latin for a mariner's compass (contrasting with Circinus, which represents a draftsman's compasses). Pyxis was introduced by Nicolas-Louis de Lacaille in the 18th century, and is counted among the 88 modern constellations.
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 constellation's brightest star. It is a blue-white star approximately Template:Convert distant and around 22,000 times as luminous as the Sun.
Pyxis is located close to the stars that formed the old constellation Argo Navis, the ship of Jason and the Argonauts. Parts of Argo Navis were the Carina (the keel or hull), the Puppis (the stern), and the Vela (the sails). These eventually became their own constellations. In the 19th century, John Herschel suggested renaming Pyxis to Malus (meaning the mast) but the suggestion was not followed.
T Pyxidis, located about 4 degrees northeast of Alpha Pyxidis, is a recurrent nova that has flared up to magnitude 7 every few decades. Also, three star systems in Pyxis have confirmed exoplanets. The Pyxis globular cluster is situated about 130,000 light-years away in the galactic halo. This region was not thought to contain globular clusters. The possibility has been raised that this object might have escaped from the Large Magellanic Cloud.<ref name="Irwin 1995"/>
HistoryEdit
In ancient Chinese astronomy, Alpha, Beta, and Gamma Pyxidis formed part of Tianmiao, a celestial temple honouring the ancestors of the emperor, along with stars from neighbouring Antlia.<ref name=startales>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The French astronomer Nicolas-Louis de Lacaille first described the constellation in French as la Boussole (the Marine Compass) in 1752,<ref name=ridpathlac>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite journal</ref> after he had observed and catalogued almost 10,000 southern stars during a two-year stay at the Cape of Good Hope. 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.Template:Efn Lacaille Latinised the name to Pixis [sic] Nautica on his 1763 chart.<ref name=wagman>Template:Cite book</ref> The Ancient Greeks identified the four main stars of Pyxis as the mast of the mythological Jason's ship, Argo Navis.<ref>Template:Cite book</ref>
German astronomer Johann Bode defined the constellation Lochium Funis, the Log and Line—a nautical device once used for measuring speed and distance travelled at sea—around Pyxis in his 1801 star atlas, but the depiction did not survive.<ref name=startales2>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> In 1844 John Herschel attempted to resurrect the classical configuration of Argo Navis by renaming it Malus the Mast, a suggestion followed by Francis Baily, but Benjamin Gould restored Lacaille's nomenclature.<ref name=wagman/> For instance, Alpha Pyxidis is referenced as α Mali in an old catalog of the United States Naval Observatory (star 3766, page 97).<ref>Template:Cite book</ref>
CharacteristicsEdit
Covering 220.8 square degrees and hence 0.535% of the sky, Pyxis ranks 65th of the 88 modern constellations by area.<ref name=tirionconst/> Its position in the Southern Celestial Hemisphere means that the whole constellation is visible to observers south of 52°N.<ref name=tirionconst>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>Template:Efn It is most visible in the evening sky in February and March.<ref name="saski_boddy2003">Template:Cite book</ref> A small constellation, it is bordered by Hydra to the north, Puppis to the west, Vela to the south, and Antlia to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Pyx".<ref name="pa30_469">Template:Cite journal</ref> The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of eight sides (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between Template:RA and Template:RA, while the declination coordinates are between −17.41° and −37.29°.<ref name="boundary">Template:Cite journal</ref>
FeaturesEdit
StarsEdit
Lacaille gave Bayer designations to ten stars now named Alpha to Lambda Pyxidis, skipping the Greek letters iota and kappa. Although a nautical element, the constellation was not an integral part of the old Argo Navis and hence did not share in the original Bayer designations of that constellation, which were split between Carina, Vela and Puppis.<ref name="wagman" /> Pyxis is a faint constellation, its three brightest stars—Alpha, Beta and Gamma Pyxidis—forming a rough line.<ref name="cambridge">Template:Cite book</ref> Overall, there are 41 stars within the constellation's borders with apparent magnitudes brighter than or equal to 6.5.Template:Efn<ref name="tirionconst" />
With an apparent magnitude of 3.68, Alpha Pyxidis is the brightest star in the constellation.<ref name="kaleralpha">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Located 880 ± 30 light-years distant from Earth,<ref name="van Leeuwen2007">Template:Cite journal</ref> it is a blue-white 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. It began life with a mass 12.1 ± 0.6 times that of the Sun, almost 15 million years ago.<ref name="Nieva 2014">Template:Cite journal</ref> Its light is dimmed by 30% due to interstellar dust, so would have a brighter magnitude of 3.31 if not for this.<ref name=kaleralpha/> The second brightest star at magnitude 3.97 is Beta Pyxidis, a yellow bright giant or supergiant of spectral type G7Ib-II that is around 435 times as luminous as the Sun,<ref name="Mcdonald">Template:Cite journal</ref> lying 420 ± 10 light-years distant away from Earth.<ref name="van Leeuwen2007"/> It has a companion star of magnitude 12.5 separated by 9 arcseconds.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Gamma Pyxidis is a star of magnitude 4.02 that lies 207 ± 2 light-years distant.<ref name="van Leeuwen2007"/> It is an orange giant of spectral type K3III that has cooled and swollen to 3.7 times the diameter of the Sun after exhausting its core hydrogen.<ref name="CADARS">Template:Cite journal</ref>
Kappa Pyxidis was catalogued but not given a Bayer designation by Lacaille, but Gould felt the star was bright enough to warrant a letter.<ref name="wagman" /> Kappa has a magnitude of 4.62 and is 560 ± 50 light-years distant.<ref name="van Leeuwen2007"/> An orange giant of spectral type K4/K5III,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Kappa has a luminosity approximately 965 times that of the Sun.<ref name="Mcdonald" /> It is separated by 2.1 arcseconds from a magnitude 10 star.<ref>Template:Cite book</ref> Theta Pyxidis is a red giant of spectral type M1III and semi-regular variable with two measured periods of 13 and 98.3 days, and an average magnitude of 4.71,<ref name="tabur">Template:Cite journal</ref> and is 500 ± 30 light-years distant from Earth.<ref name="van Leeuwen2007"/> It has expanded to approximately 54 times the diameter of the Sun.<ref name="CADARS" />
Located around 4 degrees northeast of Alpha is T Pyxidis,<ref>Template:Cite book</ref> a binary star system composed of a white dwarf with around 0.8 times the Sun's mass and a red dwarf that orbit each other every 1.8 hours. This system is located around 15,500 light-years away from Earth.<ref name="Chesneau 2011">Template:Cite journal</ref> A recurrent nova, it has brightened to the 7th magnitude in the years 1890, 1902, 1920, 1944, 1966 and 2011 from a baseline of around 14th magnitude. These outbursts are thought to be due to the white dwarf accreting material from its companion and ejecting periodically.<ref name="AAVSOT">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
TY Pyxidis is an eclipsing binary star whose apparent magnitude ranges from 6.85 to 7.5 over 3.2 days.<ref name="AAVSOTY">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The two components are both of spectral type G5IV with a diameter 2.2 times,<ref name="Strassmeier">Template:Cite journal</ref> and mass 1.2 times that of the Sun, and revolve around each other every 3.2 days.<ref>Template:Cite journal</ref> The system is classified as a RS Canum Venaticorum variable, a binary system with prominent starspot activity,<ref name="AAVSOTY" /> and lies 184 ± 5 light-years away.<ref name="van Leeuwen2007"/> The system emits X-rays, and analysing the emission curve over time led researchers to conclude that there was a loop of material arcing between the two stars.<ref name="Pres 1995">Template:Cite journal</ref> RZ Pyxidis is another eclipsing binary system, made up of two young stars less than 200,000 years old. Both are hot blue-white stars of spectral type B7V and are around 2.5 times the size of the Sun. One is around five times as luminous as the Sun and the other around four times as luminous.<ref>Template:Cite journal</ref> The system is classified as a Beta Lyrae variable, the apparent magnitude varying from 8.83 to 9.72 over 0.66 days.<ref name="AAVSORZ">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> XX Pyxidis is one of the more-studied members of a class of stars known as Delta Scuti variables<ref name="Aerts 2002">Template:Cite journal</ref>—short period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study astroseismology.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Astronomers made more sense of its pulsations when it became clear that it is also a binary star system. The main star is a white main sequence star of spectral type A4V that is around 1.85 ± 0.05 times as massive as the Sun. Its companion is most likely a red dwarf of spectral type M3V, around 0.3 times as massive as the Sun. The two are very close—possibly only 3 times the diameter of the Sun between them—and orbit each other every 1.15 days. The brighter star is deformed into an egg shape.<ref name="Aerts 2002"/>
AK Pyxidis is a red giant of spectral type M5III and semi-regular variable that varies between magnitudes 6.09 and 6.51.<ref name="AAVSOAK">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Its pulsations take place over multiple periods simultaneously of 55.5, 57.9, 86.7, 162.9 and 232.6 days.<ref name="tabur" /> UZ Pyxidis is another semi-regular variable red giant, this time a carbon star, that is around 3560 times as luminous as the Sun with a surface temperature of 3482 K, located 2116 light-years away from Earth.<ref name="Mcdonald" /> It varies between magnitudes 6.99 and 7.83 over 159 days.<ref name="AAVSOUZ">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> VY Pyxidis is a BL Herculis variable (type II Cepheid), ranging between apparent magnitudes 7.13 and 7.40 over a period of 1.24 days.<ref name="AAVSOVY">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Located around 650 light-years distant, it shines with a luminosity approximately 45 times that of the Sun.<ref name="Mcdonald" />
The closest star to Earth in the constellation is Gliese 318, a white dwarf of spectral class DA5 and magnitude 11.85.<ref name="Gaia">Template:Cite journal</ref> Its distance has been calculated to be 26 light-years,<ref>Template:Cite journal</ref> or 28.7 ± 0.5 light-years distant from Earth. It has around 45% of the Sun's mass, yet only 0.15% of its luminosity.<ref name="Subasavage">Template:Cite journal</ref> WISEPC J083641.12-185947.2 is a brown dwarf of spectral type T8p located around 72 light-years from Earth. Discovered by infrared astronomy in 2011, it has a magnitude of 18.79.<ref name="Kirkpatrick2012">Template:Cite journal</ref>
Planetary systemsEdit
Pyxis is home to three stars with confirmed planetary systems—all discovered by Doppler spectroscopy. A hot Jupiter, HD 73256 b, that orbits HD 73256 every 2.55 days, was discovered using the CORALIE spectrograph in 2003. The host star is a yellow star of spectral type G9V that has 69% of our Sun's luminosity, 89% of its diameter and 105% of its mass. Around 119 light-years away, it shines with an apparent magnitude of 8.08 and is around a billion years old.<ref name="Udry2003">Template:Cite journal</ref> HD 73267 b was discovered with the High Accuracy Radial Velocity Planet Searcher (HARPS) in 2008. It orbits HD 73267 every 1260 days, a 7 billion-year-old star of spectral type G5V that is around 89% as massive as the Sun.<ref name="Moutou2009">Template:Cite journal</ref> A red dwarf of spectral type M2.5V that has around 42% the Sun's mass, Gliese 317 is orbited by two gas giant planets. Around 50 light-years distant from Earth, it is a good candidate for future searches for more terrestrial rocky planets.<ref>Template:Cite journal</ref>
Deep sky objectsEdit
Pyxis lies in the plane of the Milky Way, although part of the eastern edge is dark, with material obscuring our galaxy arm there. NGC 2818 is a planetary nebula that lies within a dim open cluster of magnitude 8.2.<ref>Template:Cite book</ref> NGC 2818A is an open cluster that lies on line of sight with it.<ref name=inglisOC/> K 1-2 is a planetary nebula whose central star is a spectroscopic binary composed of two stars in close orbit with jets emanating from the system. The surface temperature of one component has been estimated at as high as 85,000 K.<ref name="Exter 2003">Template:Cite journal</ref> NGC 2627 is an open cluster of magnitude 8.4 that is visible in binoculars.<ref name="inglisOC">Template:Cite book</ref>
Discovered in 1995,<ref name="Irwin 1995">Template:Cite journal</ref> the Pyxis globular cluster is a 13.3 ± 1.3 billion year-old globular cluster situated around 130,000 light-years distant from Earth and around 133,000 light-years distant from the centre of the Milky Way—a region not previously thought to contain globular clusters.<ref name="1996AJ....112.2013S">Template:Cite journal</ref> Located in the galactic halo, it was noted to lie on the same plane as the Large Magellanic Cloud and the possibility has been raised that it might be an escaped object from that galaxy.<ref name="Irwin 1995"/>
NGC 2613 is a spiral galaxy of magnitude 10.5 which appears spindle-shaped as it is almost edge-on to observers on Earth.<ref>Template:Cite book</ref> Henize 2-10 is a dwarf galaxy which lies 30 million light-years away. It has a black hole of around a million solar masses at its centre. Known as a starburst galaxy due to very high rates of star formation, it has a bluish colour due to the huge numbers of young stars within it.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
See alsoEdit
NotesEdit
ReferencesEdit
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