Aldebaran
From Wikipedia, the free encyclopedia
- For the Fallen Angel Aldebaran, see Aldebaran (demon).
| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation | Taurus |
| Right ascension | 04h 35m 55.2s |
| Declination | +16° 30' 33" |
| Apparent magnitude (V) | +0.85 / +13.50 |
| Spectral Characteristics | |
| Spectral type | K5III / M2V |
| U-B color index | 1.90 / ? |
| B-V color index | 1.54 / ? |
| Variable type | Suspected / ? |
| Astrometry | |
| Radial velocity (Rv) | +53.8 km/s |
| Proper motion (μ) | RA: 62.78 mas/yr Dec.: −189.36 mas/yr |
| Parallax (π) | 50.09 ± 0.95 mas |
| Distance | 65 ± 1 ly (20 ± 0.4 pc) |
| Absolute magnitude (MV) | −0.63 / 11.98 |
| Physical Characteristics | |
| Mass | 2.5 / 0.15 M☉ |
| Radius | 25 / 0.04 R☉ |
| Luminosity | 150 / 0.00014 L☉ |
| Temperature | 4,100 / 3,050 K |
| Metallicity | 70% Sun / ? |
| Rotation | |
| Age | years |
| Other designations | |
| Database references | |
| SIMBAD | data |
Aldebaran (α Tau / α Tauri / Alpha Tauri) is the brightest star in the constellation Taurus and one of the brightest stars in the nighttime sky. Because of its location in the head of Taurus, it has historically been called the Bull's Eye.
Its name is derived from the Arabic الدبران al-dabarān meaning "the follower", a reference to the way the star follows the Pleiades star cluster in its nightly journey across the sky. Aldebaran has the appearance of being the brightest member of the more scattered Hyades cluster, which is the closest star cluster to Earth. However, it is merely located in the line of sight between the Earth and the Hyades, and is actually an independent star.
It is known as 毕宿五 (Bìxiùwŭ, the Fifth Star of the Net) in Chinese.
Aldebaran is a K5 III star, which means it is orangish, large, and has moved off of the main sequence by using all its hydrogen fuel. It has a minor companion (a dim M2 dwarf orbiting at several hundred AU). Now primarily fusing helium, the main star has expanded to a diameter of approximately 5.3 × 107 km, or about 38 times the diameter of the Sun. The Hipparcos satellite has measured it as 65.1 light years away, and it shines with 150 times the Sun's luminosity. Taken together this distance and brightness makes it the 14th brightest star, having an apparent magnitude of 0.87. It is slightly variable, of the irregular variable type, by about 0.2 magnitude.
In 1997, a possible large planet (or small brown dwarf) companion was reported, with a mass equalling that of 11 Jupiters and orbiting at a distance of 1.35 AU.
Aldebaran is one of the easiest stars to find in the night sky, partly due to its brightness and partly due to its spatial relation to one of the more noticeable asterisms in the sky. If one follows the three stars of Orion's belt from left to right (in the Northern Hemisphere) or right to left (in the Southern), the first bright star found by continuing that line is Aldebaran.
Contents |
[edit] Radial velocity variations
| Orbital elements | ||
|---|---|---|
| Semi-major axis | (a) | ~2 AU |
| Eccentricity | (e) | 0.182±0.065 |
| Orbital period | (P) | 653.8±10.1 d |
| Inclination | (i) | ?° |
| Longitude of periastron |
(ω) | 290.2±4.9° |
| Time of periastron | (τ) | 2,447,625.4±7.8 JD |
| Physical characteristics | ||
| Mass | ~11 MJ | |
| Radius | ? RJ | |
| Density | ? kg/m³ | |
| Temperature | ? K | |
| Discovery | ||
| Discovery date | 1997 | |
| Detection method(s) | Doppler Spectroscopy | |
| Discoverer(s) | Hatzes et al. | |
In 1993, radial velocity measurements of Aldebaran A, Arcturus and Pollux showed that Aldebaran A exhibited a long-period radial velocity oscillation, which could be interpreted as a substellar companion with a minimum mass 11.4 times that of Jupiter in a 643-day orbit at a separation of 2.0 AU in an eccentric orbit (eccentricity 0.147) [1]. However, all three stars surveyed showed similar oscillations yielding similar companion masses, and the authors concluded that the variation was likely to be intrinsic to the star rather than due to the gravitational effect of a companion.
An analysis of the spectrum of Aldebaran A [2] did not show any variation correlated to the 643-day radial velocity oscillation, which would be expected if the cause was intrinsic. The best orbital solution was found to be around 653.8 days with an eccentricity of 0.182, and a lower mass limit of 11 Jupiter masses. The high value for the minimum mass means that it is likely that the object, if it exists, exceeds 13 Jupiter masses and is therefore a brown dwarf. However the possibility that the oscillation is due to a pulsation or combination of pulsations still exists, and as of 2006, this companion has not been confirmed.
[edit] Aldebaran in astrology and mysticism
Astrologically, Aldebaran is a fortunate star, portending riches and honor. This star, named "Tascheter" by the Persians, is one of the four "royal stars" of the Persians from around 3000 BC. These stars were chosen in such way that they were approximately 6 hours apart in right ascension. Each of these stars was assigned to a season, Aldebaran was prominent in the sky of March and as such, it was associated with the vernal equinox.
The four royal stars with their modern and ancient Persian names:
- Aldebaran (Alpha Tauri) vernal equinox is the brightest star in the constellation Taurus.
- Regulus (Alpha Leonis) summer solstice is the brightest star in the constellation Leo.
- Antares (Alpha Scorpii) autumnal equinox the brightest star in the constellation Scorpius.
- Fomalhaut (Alpha Piscis) winter solstice is the brightest star in the constellation Piscis Austrinus.
In Hindu astronomy, Aldebaran corresponds to the Rohini Nakshatra.
To medieval astrologers it was one of fifteen Behenian stars, associated with rubies, milk thistles and the kabbalistic sign 
.
In the religion of Stregheria, Aldebaran is a fallen angel and quarter guardian of the eastern gate.
For the Dakotas (a branch of the Native American Sioux tribe), Aldebaran took on a heroic aspect. The young star was the child of the sun and the lady Blue Star. One day he desired to hunt the white buffalo (the Pleiades). After he pulled up a sapling to make a spear, a hole was made in the ground and he could see all the people of earth down below. The white buffalo took this chance to push him through. He was found by an old woman and was to be known as Old Woman's Grandson. On earth he killed many strange monsters which had been troubling the Native Americans; one monster of which was a serpent that caused drought; he killed it releasing a great stream of water that became the Mississippi River. In time, Old Woman's Grandson remembered the white buffalo and returned to hunting him in the sky to fulfill his destiny.
Was thought to be a possible origin point for the Übermenschen in Nazi mysticism.
[edit] Aldebaran in literature and media
- Aldebaran is mentioned in Billy Budd by Herman Melville in the first chapter.
- "Aldebaran" is the name of a song by Enya on the album The Celts.
- "Aldebaran of the Hyades" is the name of a song by Lustmord on the album The Place Where The Black Stars Hang.
- Farewell Aldebaran is the name of an album of late-1960s rock psychedelia by Judy Henske & Jerry Yester.
- Aldebaran is mentioned in the Rolling Stones song "2000 Light Years From Home" on the album Their Satanic Majesties Request.
- Aldebaran is the name of one of the twelve gold saints in Masami Kurumada's manga and anime Saint Seiya
- Aldebaran is mentioned in the poem "Marea" of the Greek poet Nikos Kavvadias whose work is being inspired by the sea (thalassa) and the life of seamen. Often the poet refers to the superstition of seamen over certain stars and constellations.
- Aldebaran is briefly mentioned as a location for extrasolar human colonization in Kim Stanley Robinson's book Green Mars.
- Aldebaran is the name of a town in the mmorpg "Ragnarok Online".
[edit] See also
[edit] External links
- Gl 171.1A. ARICNS. Retrieved on November 14, 2005.
- Aldebaran 2. SolStation. Retrieved on November 14, 2005.
