47 Tauri
Star in the constellation Taurus
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47 Tauri (abbreviated to 47 Tau) is a binary star in the zodiac constellation of Taurus. Parallax measurements made by the Hipparcos spacecraft put it at a distance of about 330 light-years (102 parsecs) from Earth. The system has a combined apparent magnitude of about 4.89,[2] meaning it can be faintly seen with the naked eye, according to the Bortle scale.
(5.05 + 7.32)[3]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 04h 13m 56.38482s[1] |
| Declination | +09° 15′ 49.7729″[1] |
| Apparent magnitude (V) | 4.89[2] (5.05 + 7.32)[3] |
| Characteristics | |
| Spectral type | G5III + A7V:[4] |
| U−B color index | +0.46[5] |
| B−V color index | +0.82[5] |
| Astrometry | |
| Radial velocity (Rv) | -8.2 ± 0.4[6] km/s |
| Proper motion (μ) | RA: -10.31[1] mas/yr Dec.: -30.01[1] mas/yr |
| Parallax (π) | 9.83±0.64 mas[1] |
| Distance | 330 ± 20 ly (102 ± 7 pc) |
| Orbit[3] | |
| Period (P) | 479 yr |
| Semi-major axis (a) | 1.053″ |
| Eccentricity (e) | 0.910 |
| Inclination (i) | 128.6° |
| Longitude of the node (Ω) | 52.9° |
| Periastron epoch (T) | B 1816.6 |
| Argument of periastron (ω) (secondary) | 263.0° |
| Details | |
| 47 Tau A | |
| Radius | 12.9[7] R☉ |
| Surface gravity (log g) | 2.67 ± 0.11[6] cgs |
| Temperature | 5117 ± 58[6] K |
| Metallicity [Fe/H] | -0.10 ± 0.08[6] dex |
| Other designations | |
| BD+08°652, HD 26722, HIP 19740, HR 1311, SAO 111674 | |
| Database references | |
| SIMBAD | 47 Tau |
| 47 Tau A | |
| 47 Tau B | |
47 Tauri is a visual binary, meaning that the two components can be resolved, and the orbit is derived from the positions of the two stars. The primary component is a G-type giant. Its radius is about 13 times that of the Sun.[7] The companion is likely a white-colored A-type main-sequence star that is fainter. The two stars are separated about 1.3 arcseconds away,[2] and because of their large separation, the two stars take some 479 years to complete an orbit.[3]