Tau8 Eridani
Variable star in the constellation Eridanus
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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.[4] The distance to this system can be estimated via the parallax method, yielding a value of around 380 light years.[1]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 03h 53m 42.70302s[1] |
| Declination | −24° 36′ 44.0309″[1] |
| Apparent magnitude (V) | 4.63 - 4.65[2] |
| Characteristics | |
| Spectral type | B6 V[3] |
| U−B color index | −0.48[4] |
| B−V color index | −0.13[4] |
| Variable type | SPB[2] |
| Astrometry | |
| Radial velocity (Rv) | +23[5] km/s |
| Proper motion (μ) | RA: +31.28[1] mas/yr Dec.: −7.49[1] mas/yr |
| Parallax (π) | 8.65±0.30 mas[1] |
| Distance | 380 ± 10 ly (116 ± 4 pc) |
| Absolute magnitude (MV) | −0.67[6] |
| Orbit[7] | |
| Period (P) | 454.0±0.1 d |
| Eccentricity (e) | 0.21±0.01 |
| Periastron epoch (T) | 2450497±3 JD[8] |
| Argument of periastron (ω) (secondary) | 106±3° |
| Semi-amplitude (K1) (primary) | 22.3±0.3 km/s |
| Details | |
| τ8 Eri A | |
| Mass | 5.0±0.1[9] M☉ |
| Radius | 3.81 [a] R☉ |
| Luminosity | 256[10] L☉ |
| Surface gravity (log g) | 4.00[11] cgs |
| Temperature | 11,858[10] K |
| Rotational velocity (v sin i) | 30[3] km/s |
| Age | 32.8±9.9[9] Myr |
| Other designations | |
| τ8 Eridani, τ8 Eri, 33 Eridani, CD−24°1945, HD 24587, HIP 18216, HR 1213, SAO 168925[12] | |
| Database references | |
| SIMBAD | data |
This is a single-lined[14] spectroscopic binary star system with an orbital period of about 454 days and an eccentricity of 0.21.[7] The primary component is a B-type main sequence star with a stellar classification of B6 V.[3] Gautier Mathys et al. announced that the star is variable, in 1986.[15] It is a slowly pulsating B-type star that undergoes radial-velocity variation with a frequency of 1.1569 times per day.[14] The star has about five[9] times the mass of the Sun and shines with 256 times the Sun's luminosity.[10] The outer atmosphere has an effective temperature of 11,858[10] K and may possess a longitudinal magnetic field with a strength of −140±71 G.[16]
Notes
- Derived from known luminosity and surface temperature of star.