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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h24m 39.14142s[1] |
| Declination | +37° 23′ 07.2589″[1] |
| Apparent magnitude (V) | 4.99[2] |
| Characteristics | |
| Spectral type | K4 III[3] |
| U−B color index | +1.75[2] |
| B−V color index | +1.42[2] |
| Astrometry | |
| Radial velocity (Rv) | –19.7[4] km/s |
| Proper motion (μ) | RA: +0.71[5] mas/yr Dec.: –11.51[5] mas/yr |
| Parallax (π) | 6.2101 ± 0.2221 mas[1] |
| Distance | 530 ± 20 ly (161 ± 6 pc) |
| Absolute magnitude (MV) | −0.75[6] |
| Details | |
| Radius | 43.72+1.08 −3.24[1] R☉ |
| Luminosity | 496±20[1] L☉ |
| Surface gravity (log g) | 1.75[7] cgs |
| Temperature | 4,120+162 −50[1] K |
| Metallicity [Fe/H] | –0.03[7] dex |
| Rotational velocity (v sin i) | 10[8] km/s |
| Other designations | |
σ Aur, 21 Aurigae, BD+37°1175, HD 35186, HIP 25292, HR 1773, SAO 57981[9] | |
| Database references | |
| SIMBAD | data |
Sigma Aurigae, Latinized from σ Aurigae, is a giant star in the northern constellationofAuriga. It is faintly visible to the naked eye with an apparent visual magnitude of 4.99.[2] With an annual parallax shift of 6.21 mas,[5] it is approximately 530 light-years (160 parsecs) distant from the Earth. This is an evolved giant star with a stellar classification of K4 III.[3]
Sigma Aurigae has a 12th magnitude companion at an angular separation of 8 arcseconds, as well as two fainter companions at 28 and 35" respectively.[10] All are background objects, stars much further away than Sigma itself.
Sigma Aurigae, along with λ Aur and μ Aur, were Kazwini's Al Ḣibāʽ (ألحباع), the Tent.[11] 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 σ Aur as Al Ḣibāʽ III.[12]
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