Beta Aquilae

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Beta Aquilae
Aquila constellation map.png
Location of Beta Aquilae to the upper left of center
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 55m 18.8s
Declination +06° 24′ 24″
Apparent magnitude (V) 3.71/11.4
Spectral type G8 IVvar
U−B color index 0.48
B−V color index 0.86
R−I color index 0.49
Variable type Suspected
Radial velocity (Rv) -40.3 km/s
Proper motion (μ) RA: 46.35 mas/yr
Dec.: -481.32 mas/yr
Parallax (π) 72.95 ± 0.83 mas
Distance 44.7 ± 0.5 ly
(13.7 ± 0.2 pc)
Mass 1.26 ± 0.18[1] M
Radius 3.28 ± 0.15[2] R
Luminosity 6.0 ± 0.3[2] L
Surface gravity (log g) 3.60[2] cgs
Temperature 5,100[2] K
Metallicity [Fe/H] –0.30[2] dex
Rotational velocity (v sin i) 0.9[1] km/s
Age 9.6–11.4[3] Gyr
Other designations
Alshain, Alschairn, 60 Aquilae, Gl 771, HR 7602, BD +06°4357, HD 188512, LHS 5350a, LTT 15822, SAO 125235, FK5 749, HIP 98036.
Database references
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

Beta Aquilae (β Aql, β Aquilae) is a star in the constellation Aquila. It has the traditional name Alshain from the Perso-Arabic term الشاهين aš-šāhīn "the (peregrine) falcon", perhaps by folk etymology from the Persian šāhīn tarāzū (or possibly šāhīn tara zed; see γ Aquilae), the Persian name for the asterism α, β and γ Aquilae.

In Chinese, 河鼓 (Hé Gŭ), meaning River Drum, refers to an asterism consisting of β Aquilae, Altair and γ Aql.[4] Consequently, β Aquilae itself is known as 河鼓一 (Hé Gŭ yī, English: the First Star of River Drum.)[5]

In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Unuk al Ghyrab (عنق ألغراب - únuq al-ghuraab), which was translated into Latin as Collum Corvi, meaning the crow's neck.[6]

Beta Aquilae has magnitude 3.71 and is of spectral class G8IV. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.[7] It is approximately 44.7 light years from Earth. It has a 12th magnitude optical companion, β Aquilae B, which is 13 arcseconds away in the sky.

Cultural significance[edit]

In Chinese mythology, The Princess and the Cowherd, this star and γ Aql, are children of Niulang (牛郎, The Cowherd, Altair) and Zhinü (織女, The Princess, Vega).

The Koori people of Victoria knew Alshain and γ Aquilae as the black swan wives of Bunjil (Altair), the wedge-tailed eagle.[8]

Alshain as the name[edit]

USS Alshain (AKA-55) was a United States navy ship.

See also[edit]


  1. ^ a b Bruntt, H.; et al. (July 2010), "Accurate fundamental parameters for 23 bright solar-type stars", Monthly Notices of the Royal Astronomical Society 405 (3): 1907–1923, arXiv:1002.4268, Bibcode:2010MNRAS.405.1907B, doi:10.1111/j.1365-2966.2010.16575.x 
  2. ^ a b c d e Piau, L.; et al. (February 2011), "Surface convection and red-giant radius measurements", Astronomy and Astrophysics 526: A100, arXiv:1010.3649, Bibcode:2011A&A...526A.100P, doi:10.1051/0004-6361/201014442 
  3. ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal 687 (2): 1264–1293, arXiv:0807.1686, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785 
  4. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  5. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 26, 2008.
  6. ^ Knobel, E. B. (June 1895). "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket". Monthly Notices of the Royal Astronomical Society 55: 429. Bibcode:1895MNRAS..55..429K. doi:10.1093/mnras/55.8.429. 
  7. ^ Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society 25: 1319, Bibcode:1993AAS...183.1710G, retrieved 2012-02-04 
  8. ^ Mudrooroo (1994). Aboriginal mythology : an A-Z spanning the history of aboriginal mythology from the earliest legends to the present day. London: HarperCollins. p. 4. ISBN 1-85538-306-3. 

External links[edit]