Rho Aurigae

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Rho Aurigae
Diagram showing star positions and boundaries of the Auriga constellation and its surroundings
Cercle rouge 100%.svg

The location of ρ Aurigae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension 05h 21m 48.41650s[1]
Declination +41° 48′ 16.4615″[1]
Apparent magnitude (V) +5.22[2]
Spectral type B3 V[3]
U−B color index –0.57[2]
B−V color index –0.14[2]
Radial velocity (Rv) +13.1[4] km/s
Proper motion (μ) RA: +14.42[1] mas/yr
Dec.: –37.32[1] mas/yr
Parallax (π) 6.16 ± 0.36[1] mas
Distance 530 ± 30 ly
(162 ± 9 pc)
Period (P) 34.49321 ± 0.00057 d
Eccentricity (e) 0.104 ± 0.019
Periastron epoch (T) 47962.5 ± 2.0 JD
Argument of periastron (ω)
3.4 ± 12.0°
Semi-amplitude (K1)
39.8 ± 0.8 km/s
ρ Aur A
Mass 5–7[5] M
Radius 3.2–3.4[6] R
Rotational velocity (v sin i) 55[7] km/s
ρ Aur B
Mass 2–4[5] M
Other designations
20 Aurigae, BD+41 1162, FK5 2400, HD 34759, HIP 25048, HR 1749, SAO 40269.[8]
Database references

Rho Aurigae (ρ Aur, ρ Aurigae) is the Bayer designation for a binary star system in the northern constellation of Auriga. It is faintly visible to the naked eye with an apparent visual magnitude of +5.22.[2] Judging by parallax measurements, this system is approximately 530 light-years (160 parsecs) distant from the Earth, give or take a 30 light-year margin of error.[1]

This is a single-lined spectroscopic binary system wherein the presence of a companion object is revealed by shifts in the stellar spectrum. The pair orbit each other with a period of 34.49 days and an eccentricity of 0.10.[5] The primary component of this system is a B-type main sequence star with a stellar classification of B3 V.[3] The secondary may be a B- or A-type star.[5]


This star, along with λ Aur and μ Aur, were Kazwini's Al Ḣibāʽ (ألحباع), the Tent.[9] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Ḣibāʽ were the title for three stars : λ Aur as Al Ḣibāʽ I, μ Aur as Al Ḣibāʽ II and ρ Aur as Al Ḣibāʽ III.[10]

In Chinese, 咸池 (Xián Chí), meaning Pool of Harmony, refers to an asterism consisting of ρ Aurigae, λ Aurigae and HD 36041.[11] Consequently, ρ Aurigae itself is known as 咸池一 (Xián Chí yī, English: the First Star of Pool of Harmony.)[12]


  1. ^ a b c d e f van Leeuwen, Floor (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752v1Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.  Note: see VizieR catalogue I/311.
  2. ^ a b c d Crawford, D. L.; Barnes, J. V.; Golson, J. C. (1971), "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere", The Astronomical Journal, 76: 1058, Bibcode:1971AJ.....76.1058C, doi:10.1086/111220. 
  3. ^ a b Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics, 11: 29, Bibcode:1973ARA&A..11...29M, doi:10.1146/annurev.aa.11.090173.000333. 
  4. ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E. 
  5. ^ a b c d e Horn, J.; et al. (May 1994), "The orbit of the spectroscopic binary ρ Aurigae", Astronomy and Astrophysics Supplement, 105: 119–124, Bibcode:1994A&AS..105..119H. 
  6. ^ Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367: 521–524, arXiv:astro-ph/0012289Freely accessible, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451. 
  7. ^ 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. 
  8. ^ "rho Aur -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-08-20. 
  9. ^ Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc, p. 91, ISBN 0-486-21079-0, retrieved 2010-12-12. 
  10. ^ Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), Jet Propulsion Laboratory, California Institute of Technology, retrieved 2012-08-21. 
  11. ^ (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.
  12. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 13 日

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