Aldebaran

For other uses, see Aldebaran (disambiguation). Not to be confused with Alderaan or A Tauri.
"Alpha Tauri" redirects here. For other uses, see AlphaTauri.
Aldebaran
Location of Aldebaran (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Pronunciation /ælˈdɛbərən/[1][2]
Right ascension 04h 35m 55.23907s[3]
Declination +16° 30′ 33.4885″[3]
Apparent magnitude (V) 0.86 (0.75–0.95[4])
Characteristics
Evolutionary stage Red giant branch[5]
Spectral type K5+ III[6]
Apparent magnitude (J) −2.095[7]
U−B color index +1.92[8]
B−V color index +1.44[8]
Variable type LB[4]
Astrometry
Radial velocity (Rv)+54.26±0.03[9] km/s
Proper motion (μ) RA: 63.45±0.84[3] mas/yr
Dec.: −188.94±0.65[3] mas/yr
Parallax (π)49.97 ± 0.75 mas[10]
Distance65.3 ± 1.0 ly
(20.0 ± 0.3 pc)
Absolute magnitude (MV)−0.641±0.034[10]
Details
Mass1.16±0.07[11] M☉
Radius45.1±0.1[12] R☉
Luminosity439±17[13] L☉
Surface gravity (log g)1.45±0.3[14] cgs
Temperature3,900±50[14] K
Metallicity [Fe/H]−0.33±0.1[14] dex
Rotation520 days[12]
Rotational velocity (v sin i)3.5±1.5[14] km/s
Age6.4+1.4
−1.1[11] Gyr
Other designations
Alpha Tau, α Tau, 87 Tauri, BD+16°629, GJ 171.1, 9159, HD 29139, HIP 21421, HR 1457, SAO 94027
Database references
SIMBADdata
ARICNSdata

Aldebaran (Arabic: الدَّبَران, lit. 'The Follower') (Proto-Semitic *dVbr- “bee”) is a star located in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebaran varies in brightness from an apparent visual magnitude 0.75 down to 0.95, making it the brightest star in the constellation, as well as (typically) the fourteenth-brightest star in the night sky. It is positioned at a distance of approximately 65 light-years from the Sun. The star lies along the line of sight to the nearby Hyades cluster.

Aldebaran is a red giant, meaning that it is cooler than the Sun with a surface temperature of 3,900 K, but its radius is about 45 times the Sun's, so it is over 400 times as luminous. As a giant star, it has moved off the main sequence on the Hertzsprung–Russell diagram after depleting its supply of hydrogen in the core. The star spins slowly and takes 520 days to complete a rotation. Aldebaran is believed to host a planet several times the mass of Jupiter, named Aldebaran b.

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