Tau Andromedae

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Tau Andromedae
Diagram showing star positions and boundaries of the Andromeda constellation and its surroundings
Cercle rouge 100%.svg

Location of τ Andromedae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 01h 40m 34.81645s[1]
Declination +40° 34′ 37.3742″[1]
Apparent magnitude (V) +4.94[2]
Spectral type B5 III[3]
U−B color index -0.41[2]
B−V color index -0.09[2]
Radial velocity (Rv) -14[4] km/s
Proper motion (μ) RA: +15.99[1] mas/yr
Dec.: -23.76[1] mas/yr
Parallax (π) 4.58 ± 0.25[1] mas
Distance 710 ± 40 ly
(220 ± 10 pc)
Luminosity 851[5] L
Rotational velocity (v sin i) 80[6] km/s
Other designations
53 And, BD+39 378, HD 10205, HIP 7818, HR 477, SAO 37418.[7]
Database references

Tau Andromedae (τ And, τ Andromedae) is the Bayer designation for a star in the northern constellation of Andromeda. It has an apparent visual magnitude of +4.94,[2] which is bright enough to be viewed from dark suburban skies. From parallax measurements made during the Hipparcos mission, the distance to this star can be estimated as roughly 710 light-years (220 parsecs) from Earth. The brightness of this star is diminished by 0.24 in magnitude due to extinction caused by intervening gas and dust.[3] It is approximately 681 light years from Earth.

The spectrum of this star matches a stellar classification of B5 III,[3] with the luminosity class of III indicating that this is a giant star. It is radiating about 851 times the luminosity of the Sun.[5]


In Chinese, 天大將軍 (Tiān Dà Jiāng Jūn), meaning Heaven's Great General, refers to an asterism consisting of τ Andromedae, γ Andromedae, φ Persei, 51 Andromedae, 49 Andromedae, χ Andromedae, υ Andromedae, 56 Andromedae, β Trianguli, γ Trianguli and δ Trianguli. Consequently, τ Andromedae itself is known as 天大將軍七 (Tiān Dà Jiāng Jūn qī, English: the Seventh Star of Heaven's Great General.).[8]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c d Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ a b c van Belle, Gerard T.; von Braun, Kaspar (April 2009), "Directly Determined Linear Radii and Effective Temperatures of Exoplanet Host Stars", The Astrophysical Journal, 694 (2): 1085–1098, Bibcode:2009ApJ...694.1085V, arXiv:0901.1206Freely accessible, doi:10.1088/0004-637X/694/2/1085. 
  4. ^ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953GCRV..C......0W. 
  5. ^ a b van Belle, G. T.; et al. (May 2008), "The Palomar Testbed Interferometer Calibrator Catalog", The Astrophysical Journal Supplement Series, 176 (1): 276–292, Bibcode:2008ApJS..176..276V, arXiv:0711.4194Freely accessible, doi:10.1086/526548. 
  6. ^ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590. 
  7. ^ "tau And -- Variable Star", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-06-24. 
  8. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 10 日

External links[edit]