Rho Aurigae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 21m 48.417s |
| Declination | +41° 48′ 16.46″ |
| Apparent magnitude (V) | +5.22 |
| Characteristics | |
| Spectral type | B5 V |
| U−B color index | −0.57 |
| B−V color index | −0.14 |
| Astrometry | |
| Radial velocity (Rv) | +16.3±2.2 km/s |
| Proper motion (μ) | RA: +15.053 mas/yr Dec.: −37.695 mas/yr |
| Parallax (π) | 5.2029±0.1327 mas |
| Distance | 630 ± 20 ly (192 ± 5 pc) |
| Orbit | |
| 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) (secondary) | 3.4±12.0° |
| Semi-amplitude (K1) (primary) | 39.8±0.8 km/s |
| Details | |
| ρ Aur A | |
| Mass | 5–7 M☉ |
| Radius | 3.2–3.4 R☉ |
| Rotational velocity (v sin i) | 55 km/s |
| ρ Aur B | |
| Mass | 2–4 M☉ |
| Other designations | |
| ρ Aurigae, 20 Aurigae, BD+41 1162, FK5 2400, GC 6556, HD 34759, HIP 25048, HR 1749, SAO 40269, PPM 48030 | |
| Database references | |
| SIMBAD | data |
Rho Aurigae is a binary star system in the northern constellation of Auriga. Its name is a Bayer designation that is Latinized from ρ Aurigae, and abbreviated Rho Aur or ρ Aur. This system is faintly visible to the naked eye with an apparent visual magnitude of +5.22. Judging by parallax measurements, this system is approximately 630 light-years (190 parsecs) distant from the Earth, give or take a 20-light-year margin of error. It is drifting further away from the Sun with a radial velocity of +16 km/s.
ρ Aurigae is a single-lined spectroscopic binary system; 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 orbital eccentricity of 0.10.
The primary component of this system is a B-type main-sequence star defined as a standard star for the stellar classification of B5 V. The deduced mass of the secondary and the lack of evidence for it in the spectrum suggest it may be a B- or A-type star somewhat less luminous than the primary.