Zeta Tauri
Zeta Tauri (ζ Tauri, abbreviated Zeta Tau, ζ Tau) is a binary star in the zodiac constellation of Taurus, the Bull. It has an apparent visual magnitude of about 3.0, which is bright enough to be seen with the naked eye. Parallax measurements place it at a distance of roughly 440 light-years from the Sun.
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Taurus |
| Right ascension | 05h 37m 38.68542s |
| Declination | +21° 08′ 33.1588″ |
| Apparent magnitude (V) | 3.010 (2.88–3.17) |
| Characteristics | |
| Spectral type | B2 IIIpe |
| U−B color index | −0.749 |
| B−V color index | −0.164 |
| Variable type | γ Cas |
| Astrometry | |
| Radial velocity (Rv) | +20 km/s |
| Proper motion (μ) | RA: +1.78 mas/yr Dec.: −20.07 mas/yr |
| Parallax (π) | 7.33 ± 0.82 mas |
| Distance | approx. 440 ly (approx. 140 pc) |
| Absolute magnitude (MV) | −2.67 |
| Orbit | |
| Period (P) | 132.987 d |
| Semi-major axis (a) | 1.17 AU |
| Eccentricity (e) | 0.0 (assumed) |
| Inclination (i) | 92.8° |
| Longitude of the node (Ω) | −58.0° |
| Periastron epoch (T) | 2,447,025.6 HJD |
| Argument of periastron (ω) (secondary) | 0.0 (assumed)° |
| Semi-amplitude (K1) (primary) | 7.43 km/s |
| Details | |
| ζ Tau A | |
| Mass | 11.2 M☉ |
| Radius | 5.5 R☉ |
| Luminosity | 4,169 L☉ |
| Temperature | 15,500 K |
| Rotational velocity (v sin i) | 125 km/s |
| Age | 22.5 ± 2.6 Myr |
| ζ Tau B | |
| Mass | 0.94 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
The two components are designated Zeta Tauri A (officially named Tianguan /tiænˈɡwɑːn/) and Zeta Tauri B.
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