Sigma Aurigae

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

The location of σ Aurigae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Auriga
Right ascension 05h 24m 39.14261s[1]
Declination +37° 23′ 07.2494″[1]
Apparent magnitude (V) 4.99[2]
Spectral type K4 III[3]
U−B color index +1.75[2]
B−V color index +1.42[2]
R−I color index 0.53
Radial velocity (Rv) –19.7[4] km/s
Proper motion (μ) RA: +0.71[1] mas/yr
Dec.: –11.51[1] mas/yr
Parallax (π) 6.98 ± 0.33[1] mas
Distance 470 ± 20 ly
(143 ± 7 pc)
Surface gravity (log g) 1.75[5] cgs
Temperature 4,080[5] K
Metallicity [Fe/H] –0.03[5] dex
Rotational velocity (v sin i) 10[6] km/s
Other designations
21 Aurigae, BD+37°1175, HD 35186, HIP 25292, HR 1773, SAO 57981.[7]
Database references

Sigma Aurigae (σ Aur, σ Aurigae) is the Bayer designation for a double star[8] in the northern constellation of Auriga. It is faintly visible to the naked eye with an apparent visual magnitude of 4.99.[2] With an annual parallax shift of 6.98 mas,[1] it is approximately 470 light-years (140 parsecs) distant from the Earth. This is an evolved giant star with a stellar classification of K4 III.[3] It has a magnitude 11.2 companion at an angular separation of 8.7 arcseconds.[8]


  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 Argue, A. N. (1966), "UBV photometry of 550 F, G and K type stars", Monthly Notices of the Royal Astronomical Society, 133: 475–493, Bibcode:1966MNRAS.133..475A, doi:10.1093/mnras/133.4.475. 
  3. ^ a b Roman, Nancy G. (July 1952), "The Spectra of the Bright Stars of Types F5-K5", Astrophysical Journal, 116: 122, Bibcode:1952ApJ...116..122R, doi:10.1086/145598. 
  4. ^ Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, arXiv:astro-ph/0409579Freely accessible, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272. 
  5. ^ a b c McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series, 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527. 
  6. ^ Bernacca, P. L.; Perinotto, M. (1970), "A catalogue of stellar rotational velocities", Contributi Osservatorio Astronomico di Padova in Asiago, 239 (1), Bibcode:1970CoAsi.239....1B. 
  7. ^ "sig Aur -- Star in double system", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-08-22. 
  8. ^ a b Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 

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