Rho Aurigae
Binary star system in the constellation Auriga
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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.[2] 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.[1] It is drifting further away from the Sun with a radial velocity of +16 km/s.[4]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 21m 48.417s[1] |
| Declination | +41° 48′ 16.46″[1] |
| Apparent magnitude (V) | +5.22[2] |
| Characteristics | |
| Evolutionary stage | main sequence[1] |
| Spectral type | B5 V[3] |
| U−B color index | −0.57[2] |
| B−V color index | −0.14[2] |
| Astrometry | |
| Radial velocity (Rv) | +16.3±2.2[4] km/s |
| Proper motion (μ) | RA: +15.053 mas/yr[1] Dec.: −37.695 mas/yr[1] |
| Parallax (π) | 5.2029±0.1327 mas[1] |
| Distance | 630 ± 20 ly (192 ± 5 pc) |
| Orbit[5] | |
| 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[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 | |
| ρ Aurigae, 20 Aurigae, BD+41 1162, FK5 2400, GC 6556, HD 34759, HIP 25048, HR 1749, SAO 40269, PPM 48030[8] | |
| Database references | |
| SIMBAD | data |
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.[5]
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.[3] 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.[5]
Name
In Chinese, 咸池 (Xián Chí), meaning Pool of Harmony, refers to an asterism consisting of ρ Aurigae, λ Aurigae and HD 36041.[9] Consequently, the Chinese name for ρ Aurigae itself is 咸池一 (Xián Chí yī, English: the First Star of Pool of Harmony).[10]