Tau8 Eridani
Tau8 Eridani, Latinized from τ8 Eridani, is a binary star system in the constellation Eridanus. It is visible to the naked eye with a combined apparent visual magnitude of 4.65. The distance to this system can be estimated via the parallax method, yielding a value of around 380 light years.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 03h 53m 42.70302s |
| Declination | −24° 36′ 44.0309″ |
| Apparent magnitude (V) | 4.63 - 4.65 |
| Characteristics | |
| Spectral type | B6 V |
| U−B color index | −0.48 |
| B−V color index | −0.13 |
| Variable type | SPB |
| Astrometry | |
| Radial velocity (Rv) | +23 km/s |
| Proper motion (μ) | RA: +31.28 mas/yr Dec.: −7.49 mas/yr |
| Parallax (π) | 8.65 ± 0.30 mas |
| Distance | 380 ± 10 ly (116 ± 4 pc) |
| Absolute magnitude (MV) | −0.67 |
| Orbit | |
| Period (P) | 459±4 d |
| Eccentricity (e) | 0.18±0.02 |
| Periastron epoch (T) | 2450954±7 JD |
| Argument of periastron (ω) (secondary) | 106±5° |
| Semi-amplitude (K1) (primary) | 21.7±0.4 km/s |
| Details | |
| τ8 Eri A | |
| Mass | 5.0±0.1 M☉ |
| Luminosity | 256 L☉ |
| Surface gravity (log g) | 4.00 cgs |
| Temperature | 11,858 K |
| Rotational velocity (v sin i) | 30 km/s |
| Age | 32.8±9.9 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a single-lined spectroscopic binary star system with an orbital period of about 459 days and an eccentricity of 0.18. The primary component is a B-type main sequence star with a stellar classification of B6 V. It is a slowly pulsating B-type star that undergoes radial-velocity variation with a frequency of 1.1569 times per day. The star has about five times the mass of the Sun and shines with 256 times the Sun's luminosity. The outer atmosphere has an effective temperature of 11,858 K and may possess a longitudinal magnetic field with a strength of −140±71 G.