Tau1 Eridani
Tau1 Eridani, Latinized from τ1 Eridani, is a binary star system in the constellation Eridanus. It has an apparent magnitude of 4.46, making it visible to the naked eye in suitably dark conditions. This a spectroscopic binary with an orbital period of 958 days. It is located about 46 light years from the Earth. At present, the system is moving away from the Sun with a radial velocity of +26 km/s. About 305,000 years ago, it made perihelion passage at an estimated distance of 30.5 ly (9.35 pc).
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 02h 45m 06.18710s |
| Declination | −18° 34′ 21.2149″ |
| Apparent magnitude (V) | 4.46 |
| Characteristics | |
| Spectral type | F7V |
| U−B color index | +0.00 |
| B−V color index | +0.48 |
| Astrometry | |
| Radial velocity (Rv) | +25.9 km/s |
| Proper motion (μ) | RA: +334.20 mas/yr Dec.: +37.19 mas/yr |
| Parallax (π) | 70.32 ± 1.83 mas |
| Distance | 46 ± 1 ly (14.2 ± 0.4 pc) |
| Absolute magnitude (MV) | +3.68 |
| Orbit | |
| Period (P) | 958 d |
| Eccentricity (e) | 0.45 |
| Periastron epoch (T) | 39391.9 |
| Argument of periastron (ω) (secondary) | 180° |
| Details | |
| Mass | 1.15 M☉ |
| Surface gravity (log g) | 4.34 cgs |
| Temperature | 6,231 K |
| Metallicity [Fe/H] | −0.08 ± 0.06 dex |
| Rotation | 3.847 d |
| Rotational velocity (v sin i) | 28.02 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Tau1 Eridani was a latter designation of 90 Ceti.
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