Sigma Aurigae, an orange giant star in Auriga
Sigma Aurigae is an orange giant star in the constellation Auriga. At 513 light years away, it shines at an apparent visual magnitude of 5.00.
Sigma Aurigae (HIP 25292)
Sigma Aurigae is an orange giant star in the constellation Auriga. At 513 light years away, it shines at an apparent visual magnitude of 5.00. It is moving through the Galaxy at a speed of 21.1 km/s relative to the Sun.
Sky position: RA 5h 24.7m, Dec +37° 23.1'
Common designations: Sigma Aurigae, 21 Aurigae, HR 1773, HD 35186, HIP 25292, Gaia DR3 184433149893809024
Sigma Aurigae has the spectral type K3IIICN+2. K-type stars are orange stars with surface temperatures of about 3,900 to 5,300 K. Their spectra are rich in neutral metal lines and, in the cooler examples, molecular bands. Its luminosity class III marks it as a giant: an evolved star that has left the main sequence and swollen to many times its original size.
How to find Sigma Aurigae in the sky
Sigma Aurigae lies in Auriga. With a declination of +37° 23.1', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 53° S. Observers poleward of latitude 53° N see it as circumpolar: it never sets. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around January, which makes the weeks around that month the best time to observe it.
Tabulated data for Sigma Aurigae
Astrometry and spectroscopy
| Right Ascension (J2000) | 81.16308950° (5h 24.7m) |
| Declination (J2000) | 37.38534910° (+37° 23.1') |
| Galactic Longitude | 170.52443925° |
| Galactic Latitude | 0.88428392° |
| Proper motion RA | -0.56 mas/yr |
| Proper motion Dec | -10.95 mas/yr |
| Parallax | 6.35 ± 0.09 mas |
| Spectral Type | K3IIICN+2 |
| Radial Velocity | -19.40 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| B | 6.43 | 0.45 |
| V | 5.00 | -0.99 |
| J | 2.48 | -3.51 |
| H | 1.83 | -4.16 |
| K | 1.73 | -4.26 |
Colour index B-V: +1.44
Derivations
- Heliocentric distance: 157.37 pc (513 light years) (1.4% margin of error)
- Absolute visual magnitude: -0.99
- Transverse velocity: 8.2 km/s
- Space velocity relative to the Sun: 21.1 km/s
- Galactic position (X, Y, Z): -155.2 pc, 25.9 pc, 2.4 pc
- Galactic velocity (U, V, W): 18.0 km/s, -9.6 km/s, -5.2 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.