Constellation | |
![]() | |
Abbreviation | Pyx |
---|---|
Genitive | Pyxidis |
Pronunciation | /ˈpɪksɪs/ , genitive /ˈpɪksɪdɪs/ |
Symbolism | The compass box |
Right ascension | 9h |
Declination | −30° |
Quadrant | SQ2 |
Area | 221 sq. deg. (65th) |
Main stars | 3 |
Bayer/Flamsteed stars | 10 |
Stars with planets | 3 |
Stars brighter than 3.00m | 0 |
Stars within 10.00 pc (32.62 ly) | 1 |
Brightest star | α Pyx (3.68 m ) |
Messier objects | 0 |
Bordering constellations | Hydra Puppis Vela Antlia |
Visible at latitudes between +50° and −90°. Best visible at 21:00 (9 p.m.) during the month of March. |
Pyxis [lower-alpha 1] 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 880 light-years (270 parsecs ) 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. [3]
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. [4]
The French astronomer Nicolas-Louis de Lacaille first described the constellation in French as la Boussole (the Marine Compass) in 1752, [5] [6] 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. [lower-alpha 2] Lacaille Latinised the name to Pixis [sic] Nautica on his 1763 chart. [7] The Ancient Greeks identified the four main stars of Pyxis as the mast of the mythological Jason's ship, Argo Navis . [8]
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. [9] 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. [7]
Covering 220.8 square degrees and hence 0.535% of the sky, Pyxis ranks 65th of the 88 modern constellations by area. [10] Its position in the Southern Celestial Hemisphere means that the whole constellation is visible to observers south of 52°N. [10] [lower-alpha 3] It is most visible in the evening sky in February and March. [11] 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". [12] 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 8h 27.7m and 9h 27.6m, while the declination coordinates are between −17.41° and −37.29°. [13]
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. [7] Pyxis is a faint constellation, its three brightest stars—Alpha, Beta and Gamma Pyxidis—forming a rough line. [14] Overall, there are 41 stars within the constellation's borders with apparent magnitudes brighter than or equal to 6.5. [lower-alpha 4] [10]
With an apparent magnitude of 3.68, Alpha Pyxidis is the brightest star in the constellation. [16] Located 880 ± 30 light-years distant from Earth, [17] 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. [18] Its light is dimmed by 30% due to interstellar dust, so would have a brighter magnitude of 3.31 if not for this. [16] 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, [19] lying 420 ± 10 light-years distant away from Earth. [17] It has a companion star of magnitude 12.5 separated by 9 arcseconds. [20] Gamma Pyxidis is a star of magnitude 4.02 that lies 207 ± 2 light-years distant. [17] 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. [21]
Kappa Pyxidis was catalogued but not given a Bayer designation by Lacaille, but Gould felt the star was bright enough to warrant a letter. [7] Kappa has a magnitude of 4.62 and is 560 ± 50 light-years distant. [17] An orange giant of spectral type K4/K5III, [22] Kappa has a luminosity approximately 965 times that of the Sun. [19] It is separated by 2.1 arcseconds from a magnitude 10 star. [23] 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, [24] and is 500 ± 30 light-years distant from Earth. [17] It has expanded to approximately 54 times the diameter of the Sun. [21]
Located around 4 degrees northeast of Alpha is T Pyxidis, [25] 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. [26] 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. [27]
TY Pyxidis is an eclipsing binary star whose apparent magnitude ranges from 6.85 to 7.5 over 3.2 days. [28] The two components are both of spectral type G5IV with a diameter 2.2 times, [29] and mass 1.2 times that of the Sun, and revolve around each other every 3.2 days. [30] The system is classified as a RS Canum Venaticorum variable, a binary system with prominent starspot activity, [28] and lies 184 ± 5 light-years away. [17] 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. [31] 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. [32] The system is classified as a Beta Lyrae variable, the apparent magnitude varying from 8.83 to 9.72 over 0.66 days. [33] XX Pyxidis is one of the more-studied members of a class of stars known as Delta Scuti variables [34] —short period (six hours at most) pulsating stars that have been used as standard candles and as subjects to study astroseismology. [35] 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. [34]
AK Pyxidis is a red giant of spectral type M5III and semi-regular variable that varies between magnitudes 6.09 and 6.51. [36] Its pulsations take place over multiple periods simultaneously of 55.5, 57.9, 86.7, 162.9 and 232.6 days. [24] 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. [19] It varies between magnitudes 6.99 and 7.83 over 159 days. [37] 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. [38] Located around 650 light-years distant, it shines with a luminosity approximately 45 times that of the Sun. [19]
The closest star to Earth in the constellation is Gliese 318, a white dwarf of spectral class DA5 and magnitude 11.85. [39] Its distance has been calculated to be 26 light-years, [40] 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. [41] 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. [42]
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. [43] 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. [44] 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. [45]
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. [46] NGC 2818A is an open cluster that lies on line of sight with it. [47] 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. [48] NGC 2627 is an open cluster of magnitude 8.4 that is visible in binoculars. [47]
Discovered in 1995, [3] 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. [49] 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. [3]
NGC 2613 is a spiral galaxy of magnitude 10.5 which appears spindle-shaped as it is almost edge-on to observers on Earth. [50] 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. [51]
Antlia is a constellation in the Southern Celestial Hemisphere. Its name means "pump" in Latin and Greek; it represents an air pump. Originally Antlia Pneumatica, the constellation was established by Nicolas-Louis de Lacaille in the 18th century. Its non-specific (single-word) name, already in limited use, was preferred by John Herschel then welcomed by the astronomic community which officially accepted this. North of stars forming some of the sails of the ship Argo Navis, Antlia is completely visible from latitudes south of 49 degrees north.
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 wrongly believed to lack feet. First depicted on a celestial globe by Petrus Plancius in 1598, it was charted on a star atlas by Johann Bayer in his 1603 Uranometria. The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations in 1756.
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 remains one of the 88 modern constellations. 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 her in the heavens. Other cultures likened the pattern to a circle of elders, an eagle's nest, a bear's den or a smokehole. Ptolemy also listed a southern counterpart, Corona Australis, with a similar pattern.
Fornax is a constellation in the southern celestial hemisphere, partly ringed by the celestial river Eridanus. Its name is Latin for furnace. It was named by French astronomer Nicolas Louis de Lacaille in 1756. Fornax is one of the 88 modern constellations.
Hydrus is a small constellation in the deep southern sky. It was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman and it first appeared on a 35-cm (14 in) diameter celestial globe published in late 1597 in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars and gave their Bayer designations in 1756. Its name means "male water snake", as opposed to Hydra, a much larger constellation that represents a female water snake. It remains below the horizon for most Northern Hemisphere observers.
Microscopium is a minor constellation in the southern celestial hemisphere, one of twelve created in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. The 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.
Piscis Austrinus is a constellation in the southern celestial hemisphere. The name is Latin for "the southern fish", in contrast with the larger constellation Pisces, which represents a pair of fish. Before the 20th century, it was also known as Piscis Notius. Piscis Austrinus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. 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.
Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union. Although it dates to antiquity, Sagitta has no star brighter than 3rd magnitude and has the third-smallest area of any constellation.
Tucana is a constellation in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the late sixteenth century by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Tucana first appeared on a 35-centimetre-diameter (14 in) celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's 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".
Telescopium is a minor constellation in the southern celestial hemisphere, one of twelve named in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name is a Latinized form of the Greek word for telescope. Telescopium was later much reduced in size by Francis Baily and Benjamin Gould.
Vela is a constellation in the southern sky, which contains the Vela Supercluster. Its name is Latin for the sails of a ship, and it was originally part of a larger constellation, the ship Argo Navis, which was later divided into three parts, the others being Carina and Puppis. With an apparent magnitude of 1.8, its brightest star is the hot blue multiple star Gamma Velorum, one component of which is the closest and brightest Wolf-Rayet star in the sky. 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.
Phoenix is a minor constellation in the southern sky. Named after the mythical 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 and gave their Bayer designations in 1756. 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.
Norma is a small constellation in the Southern Celestial Hemisphere between Ara and Lupus, one of twelve drawn up in the 18th century by French astronomer Nicolas-Louis de Lacaille and one of several depicting scientific instruments. Its name is Latin for normal, referring to a right angle, and is variously considered to represent a rule, a carpenter's square, a set square or a level. It remains one of the 88 modern constellations.
Circinus is a small, faint constellation in the southern sky, first defined in 1756 by the French astronomer Nicolas-Louis de Lacaille. Its name is Latin for compass, referring to the drafting tool used for drawing circles. Its brightest star is Alpha Circini, with an apparent magnitude of 3.19. Slightly variable, it is the brightest rapidly oscillating Ap star in the night sky. AX Circini is a Cepheid variable visible with the unaided eye, and BX Circini is a faint star thought to have been formed from the merger of two white dwarfs. Two sun-like stars have planetary systems: HD 134060 has two small planets, and HD 129445 has a Jupiter-like planet. Supernova SN 185 appeared in Circinus in 185 AD and was recorded by Chinese observers. Two novae have been observed more recently, in the 20th century.
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 constellation's 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 (visual) magnitude 1.2 in 1925 before fading into obscurity.
Musca is a small constellation in the deep southern sky. It was one of 12 constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman, and it first appeared on a celestial globe 35 cm (14 in) in diameter published in 1597 in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. It was also known as Apis for 200 years. Musca remains below the horizon for most Northern Hemisphere observers.
Horologium is a constellation of six stars faintly visible in the southern celestial hemisphere. It was first described by the French astronomer Nicolas-Louis de Lacaille in 1756 and visualized by him as a clock with a pendulum and a second hand. In 1922 the constellation was redefined by the International Astronomical Union (IAU) as a region of the celestial sphere containing Lacaille's stars, and has since been an IAU designated constellation. Horologium's associated region is wholly visible to observers south of 23°N.
Mensa is a constellation in the Southern Celestial Hemisphere near the south celestial pole, one of fourteen constellations drawn up in the 18th century by French astronomer Nicolas-Louis de Lacaille. Its name is Latin for table, though it originally commemorated Table Mountain and was known as "Mons Mensae". One of the eighty-eight constellations designated by the International Astronomical Union (IAU), it covers a keystone-shaped wedge of sky 153.5 square degrees in area. Other than the south polar constellation of Octans, it is the most southerly of constellations and is observable only south of the 5th parallel of the Northern Hemisphere.
RZ Pyxidis is eclipsing binary system in the constellation Pyxis, 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. The system is classified as a Beta Lyrae variable, he apparent magnitude ranging from 8.83 to 9.72 over 0.66 days.
XX Pyxidis is a star located in the constellation Pyxis. It has an apparent magnitude that varies slightly at about 11.5, and is about 2,300 light years away.