Centaurus
Encyclopedia
Centaurus is a bright constellation in the southern sky
. One of the largest constellations, Centaurus was included among the 48 constellation
s listed by the 2nd century astronomer Ptolemy
, and it remains one of the 88 modern constellations.
system, a triple star system consisting of a bright binary star
to which the much fainter red dwarf
Proxima Centauri
is gravitationally bound; Proxima is the nearest known star
to the Sun
.
In addition to Alpha Centauri (the 4th brightest star in the sky), a second first magnitude
star, Hadar
, is part of Centaurus.
BPM 37093
is a white dwarf
star whose carbon
atoms are thought to have formed a crystalline structure. Since diamond
also consists of carbon arranged in a crystalline lattice (though of a different configuration), scientists have nicknamed this star "Lucy" after the Beatles song "Lucy in the Sky with Diamonds."
, despite being listed as the constellation's "omega" star, is in fact a globular cluster
, also classified as NGC 5139. It is the largest and brightest globular cluster in the Milky Way
.
The nearby lenticular galaxy
, radio source Centaurus A
(NGC 5128), the elliptical galaxy
ESO 325-G004, and the spiral galaxy NGC 4444
are all located in this constellation.
. Thousands of years from now Centaurus will, once again, be at lower latitudes and be visible worldwide.
The figure of Centaurus can be traced back to a Babylonian constellation known as the Bison-man (MUL.GUD.ALIM). This being was depicted in two major forms: firstly, as a 4-legged bison with a human head, and secondly, as a being with a man's head and torso attached to the rear legs and tail of a bull or bison. It has been closely associated with the Sun god Utu-Shamash from very early times.
The Greeks depicted the constellation as a centaur
and gave it its current name. The name Centaurus
in mythology is given not to a centaur but a deformed human who would later mate with mares and spawn the centaur race. It was mentioned by Eudoxus
in the 4th century BCE and Aratus
in the 3rd century BCE. In the 2nd century AD, Claudius Ptolemy catalogued 37 stars in Centaurus. Large as it is now, in earlier times it was even larger, as the constellation Lupus
was treated as an asterism
within Centaurus, portrayed in illustrations as an unspecified animal either in the centaur's grasp or impaled on its spear. The Southern Cross
, which is now regarded as a separate constellation, was treated by the ancients as a mere asterism formed of the stars composing the centaur's legs. Additionally, what is now the minor constellation Circinus
was treated as undefined stars under the centaur's front hooves.
According to the Roman poet Ovid
(Fasti v.379), the constellation honors the centaur Chiron
, who was tutor to many of the earlier Greek heroes including Heracles
(Hercules), Theseus, and Jason
, the leader of the Argonauts. However, most authorities consider Sagittarius
to be the civilized Chiron, while Centaurus represents a more uncouth member of the species.
, the stars of Centaurus are found in three areas: the Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng), the Vermillion Bird of the South
(南方朱雀, Nán Fāng Zhū Què), and the Southern Asterisms (近南極星區, Jìnnánjíxīngōu). Not all of the stars of Centaurus can be seen from China, and the unseen stars were classified among the Southern Asterisms by Xu Guangqi
, based on his study of western star charts. However, most of the brightest stars of Centaurus, including α Cen
, θ Cen
, ε Cen
and η Cen, can be seen in the Chinese sky.
ships, USS Centaurus (AKA-17)
and USS Centaurus (AK-264), are named after the constellation.
Celestial sphere
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. Projected upward from Earth's equator and poles are the...
. One of the largest constellations, Centaurus was included among the 48 constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
s listed by the 2nd century astronomer Ptolemy
Ptolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...
, and it remains one of the 88 modern constellations.
Stars
Centaurus contains the Alpha CentauriAlpha Centauri
Alpha Centauri is the brightest star in the southern constellation of Centaurus...
system, a triple star system consisting of a bright binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
to which the much fainter red dwarf
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
Proxima Centauri
Proxima Centauri
Proxima Centauri is a red dwarf star about 4.2 light-years distant in the constellation of Centaurus. It was discovered in 1915 by Robert Innes, the Director of the Union Observatory in South Africa, and is the nearest known star to the Sun, although it is too faint to be seen with the naked eye...
is gravitationally bound; Proxima is the nearest known star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
to the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
.
In addition to Alpha Centauri (the 4th brightest star in the sky), a second first magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
star, Hadar
Beta Centauri
Beta Centauri , also known as Hadar or Agena, is the second brightest star in the constellation Centaurus and the tenth brightest star in the night sky. Beta Centauri is a B1 III blue-white giant star that the astrometric Hipparcos satellite calculates as about 161 parsecs or 525 light-years from...
, is part of Centaurus.
BPM 37093
BPM 37093
BPM 37093 is a variable white dwarf star of the DAV, or ZZ Ceti, type, with a hydrogen atmosphere and an unusually high mass of approximately 1.1 times the Sun's. It is about 50 light-years from Earth, in the constellation Centaurus, and vibrates; these pulsations cause its luminosity to vary...
is a white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
star whose carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
atoms are thought to have formed a crystalline structure. Since diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
also consists of carbon arranged in a crystalline lattice (though of a different configuration), scientists have nicknamed this star "Lucy" after the Beatles song "Lucy in the Sky with Diamonds."
Deep sky objects
ω CentauriOmega Centauri
Omega Centauri or NGC 5139 is a globular clusterin the constellation of Centaurus, discovered by Edmond Halley in 1677 who listed it as a nebula. Omega Centauri had been listed in Ptolemy's catalog 2000 years ago as a star. Lacaille included it in his catalog as number I.5...
, despite being listed as the constellation's "omega" star, is in fact a globular cluster
Globular cluster
A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is...
, also classified as NGC 5139. It is the largest and brightest globular cluster in the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
.
The nearby lenticular galaxy
Lenticular galaxy
A lenticular galaxy is a type of galaxy which is intermediate between an elliptical galaxy and a spiral galaxy in galaxy morphological classification schemes. Lenticular galaxies are disk galaxies which have used up or lost most of their interstellar matter and therefore have very little ongoing...
, radio source Centaurus A
Centaurus A
Centaurus A is a prominent galaxy in the constellation of Centaurus. There is considerable debate in the literature regarding the galaxy's fundamental properties such as its Hubble type and distance...
(NGC 5128), the elliptical galaxy
Elliptical galaxy
An elliptical galaxy is a galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile. They range in shape from nearly spherical to highly flat and in size from hundreds of millions to over one trillion stars...
ESO 325-G004, and the spiral galaxy NGC 4444
NGC 4444
NGC 4444 is an intermediate spiral galaxy in the constellation Centaurus. The morphological classification places it midway on the continuum between a barred spiral and an unbarred spiral , with an inner region that lies between a ring-like and a purely spiral form , and medium- to loosely-wound...
are all located in this constellation.
History
While Centaurus now has a high southern latitude, at the dawn of civilization it was an equatorial constellation. Precession has been slowly shifting it southward for millennia, and it is now close to its maximal southern declinationDeclination
In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...
. Thousands of years from now Centaurus will, once again, be at lower latitudes and be visible worldwide.
The figure of Centaurus can be traced back to a Babylonian constellation known as the Bison-man (MUL.GUD.ALIM). This being was depicted in two major forms: firstly, as a 4-legged bison with a human head, and secondly, as a being with a man's head and torso attached to the rear legs and tail of a bull or bison. It has been closely associated with the Sun god Utu-Shamash from very early times.
The Greeks depicted the constellation as a centaur
Centaur
In Greek mythology, a centaur or hippocentaur is a member of a composite race of creatures, part human and part horse...
and gave it its current name. The name Centaurus
Centaurus (Greek mythology)
Centaurus is the father of the race of mythological beasts known as the centaurs or Ixionidae. The centaurs are half man, half horse; having the torso of a man extending where the neck of a horse should be. They were said in Greek mythology to be wild, savage, and lustful...
in mythology is given not to a centaur but a deformed human who would later mate with mares and spawn the centaur race. It was mentioned by Eudoxus
Eudoxus of Cnidus
Eudoxus of Cnidus was a Greek astronomer, mathematician, scholar and student of Plato. Since all his own works are lost, our knowledge of him is obtained from secondary sources, such as Aratus's poem on astronomy...
in the 4th century BCE and Aratus
Aratus
Aratus was a Greek didactic poet. He is best known today for being quoted in the New Testament. His major extant work is his hexameter poem Phaenomena , the first half of which is a verse setting of a lost work of the same name by Eudoxus of Cnidus. It describes the constellations and other...
in the 3rd century BCE. In the 2nd century AD, Claudius Ptolemy catalogued 37 stars in Centaurus. Large as it is now, in earlier times it was even larger, as the constellation Lupus
Lupus (constellation)
Lupus is a constellation in the southern sky. Its name is Latin for wolf. Lupus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations...
was treated as an asterism
Asterism (astronomy)
In astronomy, an asterism is a pattern of stars recognized on Earth's night sky. It may form part of an official constellation, or be composed of stars from more than one. Like constellations, asterisms are in most cases composed of stars which, while they are visible in the same general direction,...
within Centaurus, portrayed in illustrations as an unspecified animal either in the centaur's grasp or impaled on its spear. The Southern Cross
Crux
Crux is the smallest of the 88 modern constellations, but is one of the most distinctive. Its name is Latin for cross, and it is dominated by a cross-shaped asterism that is commonly known as the Southern Cross.-Visibility:...
, which is now regarded as a separate constellation, was treated by the ancients as a mere asterism formed of the stars composing the centaur's legs. Additionally, what is now the minor constellation Circinus
Circinus
The constellation Circinus is a small constellation in the southern sky, first defined in the 18th century. Its name is Latin for compass, referring to the drafting tool used for drawing circles; it should not be confused with Pyxis, a constellation that represents a mariner's...
was treated as undefined stars under the centaur's front hooves.
According to the Roman poet Ovid
Ovid
Publius Ovidius Naso , known as Ovid in the English-speaking world, was a Roman poet who is best known as the author of the three major collections of erotic poetry: Heroides, Amores, and Ars Amatoria...
(Fasti v.379), the constellation honors the centaur Chiron
Chiron
In Greek mythology, Chiron was held to be the superlative centaur among his brethren.-History:Like the satyrs, centaurs were notorious for being wild and lusty, overly indulgent drinkers and carousers, given to violence when intoxicated, and generally uncultured delinquents...
, who was tutor to many of the earlier Greek heroes including Heracles
Heracles
Heracles ,born Alcaeus or Alcides , was a divine hero in Greek mythology, the son of Zeus and Alcmene, foster son of Amphitryon and great-grandson of Perseus...
(Hercules), Theseus, and Jason
Jason
Jason was a late ancient Greek mythological hero from the late 10th Century BC, famous as the leader of the Argonauts and their quest for the Golden Fleece. He was the son of Aeson, the rightful king of Iolcus...
, the leader of the Argonauts. However, most authorities consider Sagittarius
Sagittarius (constellation)
Sagittarius is a constellation of the zodiac, the one containing the galactic center. Its name is Latin for the archer, and its symbol is , a stylized arrow. Sagittarius is commonly represented as a centaur drawing a bow...
to be the civilized Chiron, while Centaurus represents a more uncouth member of the species.
Equivalents
In Chinese astronomyChinese astronomy
Astronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...
, the stars of Centaurus are found in three areas: the Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng), the Vermillion Bird of the South
Vermilion Bird (Chinese constellation)
The Vermilion bird is one of the Four Symbols of the Chinese constellations. According to Wu Xing, the Taoist five-elemental system, it represents the fire-element, the direction south, and the season summer correspondingly. Thus it is sometimes called the Vermilion bird of the South...
(南方朱雀, Nán Fāng Zhū Què), and the Southern Asterisms (近南極星區, Jìnnánjíxīngōu). Not all of the stars of Centaurus can be seen from China, and the unseen stars were classified among the Southern Asterisms by Xu Guangqi
Xu Guangqi
Xu Guangqi , was a Chinese scholar-bureaucrat, agricultural scientist, astronomer, and mathematician in the Ming Dynasty. Xu was a colleague and collaborator of the Italian Jesuits Matteo Ricci and Sabatino de Ursis and they translated several classic Western texts into Chinese, including part of...
, based on his study of western star charts. However, most of the brightest stars of Centaurus, including α Cen
Alpha Centauri
Alpha Centauri is the brightest star in the southern constellation of Centaurus...
, θ Cen
Theta Centauri
Theta Centauri is a star in the constellation Centaurus. It is also has the traditional Arabic name Menkent...
, ε Cen
Epsilon Centauri
Epsilon Centauri is a star in the constellation Centaurus.In Chinese, , meaning Southern Gate, refers to an asterism consisting of ε Centauri and α Centauri. Consequently, ε Centauri itself is known as...
and η Cen, can be seen in the Chinese sky.
Namesakes
Two United States navyUnited States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
ships, USS Centaurus (AKA-17)
USS Centaurus (AKA-17)
USS Centaurus was an named after the constellation Centaurus. She was one of a handful of World War II AKAs manned by officers and crew from the United States Coast Guard...
and USS Centaurus (AK-264), are named after the constellation.