Omega Eridani
Omega Eridani (ω Eri) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude is 4.37. The distance to this star, as determined by the parallax method, is around 235 light years.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 04h 52m 53.66995s |
| Declination | −05° 27′ 09.6972″ |
| Apparent magnitude (V) | 4.37 |
| Characteristics | |
| Spectral type | A9 IVn |
| U−B color index | +0.12 |
| B−V color index | +0.26 |
| Astrometry | |
| Radial velocity (Rv) | −8.3 km/s |
| Proper motion (μ) | RA: −17.86 mas/yr Dec.: +25.57 mas/yr |
| Parallax (π) | 13.88 ± 0.24 mas |
| Distance | 235 ± 4 ly (72 ± 1 pc) |
| Absolute magnitude (MV) | 0.10 |
| Orbit | |
| Period (P) | 3,057 d |
| Eccentricity (e) | 0.46 |
| Periastron epoch (T) | 2419973.0 JD |
| Argument of periastron (ω) (secondary) | 227° |
| Semi-amplitude (K1) (primary) | 18.1 km/s |
| Details | |
| Radius | 6.7 R☉ |
| Luminosity | 69 L☉ |
| Surface gravity (log g) | 3.4 cgs |
| Temperature | 6,878 K |
| Metallicity [Fe/H] | 0.18 dex |
| Rotational velocity (v sin i) | 186 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a single-lined spectroscopic binary system with an orbital period of 3,057 days (8.4 years) and an eccentricity of 0.46. The primary component is an A-type subgiant star with a stellar classification of A9 IVn, where the 'n' suffix indicates a broad ("nebulous") absorption due to rotation. The projected rotational velocity is 186 km/s. This is giving the star an oblate shape with an equator that is 13% wider than the polar radius. The angular size of Omega Eridani is 0.87 mas. At an estimated distance of the star, this yields a physical size of around 6.7 times the radius of the Sun.