Ζ Tau
 Location of ζ Tauri (circled) |
|
| 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 | Eclipsing + 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 ± 0.82mas |
| 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 |
Zeta Tauri (ζ Tau, ζ Tauri) is a binary star in the zodiac constellation Taurus, the Bull, and has the proper name Tianguan. It has an apparent visual magnitude of 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 Earth.
ζ Tauri (Latinised to Zeta Tauri) is the star's Bayer designation; it also bears the Flamsteed designation of 123 Tauri.
In Chinese astronomy, ζ Tauri is called 天關, Pinyin: Tiānguān, meaning Celestial Gate, an asterism within the Net (畢宿 Bì Xiù) mansion (see also: Chinese constellation). 天關 (Tiānguān) has also been transliterated as Tien Kwan. Technically, Tiānguān refers not just to Zeta Tauri but to an asterism of which Zeta Tauri is the main star, alongside 113 Tau, 126 Tau, 128 Tau, 129 Tau, 130 Tau and 127 Tau (see Taurus (Chinese astronomy)).
The International Astronomical Union Working Group on Star Names (WGSN) gives Tianguan as the proper name of ζ Tauri.
This is a single-lined spectroscopic binary system, which means the two components are orbiting so close to each other that they can not be resolved with a telescope. Instead, the orbital motion of the primary component is indicated by Doppler effect shifts in the absorption lines in its spectrum. The two components are separated by an estimated distance of about 1.17 astronomical units, or 117% of the distance from the Earth to the Sun. They are following circular orbits with a period of nearly 133 days.
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