Pleione (star)
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 03h 49m 11.2166s |
| Declination | +24° 08′ 12.157″ |
| Apparent magnitude (V) | 4.77 - 5.50 |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | B8Vne |
| B−V color index | −0.08 |
| Variable type | γ Cas |
| Astrometry | |
| Radial velocity (Rv) | 5.10 km/s |
| Proper motion (μ) | RA: 19.496 mas/yr Dec.: −47.650 mas/yr |
| Parallax (π) | 7.2414±0.1255 mas |
| Distance | 450 ± 8 ly (138 ± 2 pc) |
| Absolute magnitude (MV) | −0.347 |
| Details | |
| Mass | 2.888 M☉ |
| Radius | 4.17±0.17 R☉ |
| Luminosity | 184 L☉ |
| Surface gravity (log g) | 3.087 cgs |
| Temperature | 11,058 K |
| Metallicity [Fe/H] | +0.02 dex |
| Rotational velocity (v sin i) | 290 km/s |
| Age | 125 Myr |
| Other designations | |
| Pleione, 28 Tau, BU Tau, BD+23°558, GC 4587, HD 23862, HIP 17851, HR 1180, SAO 76229 | |
| Database references | |
| SIMBAD | data |
Pleione is a binary star system in the Pleiades star cluster, within the Taurus constellation. It has the variable star designation BU Tauri (BU Tau) and the Flamsteed designation 28 Tauri (28 Tau). Pleione is located close on the sky to the brighter star Atlas, so is difficult for stargazers to distinguish with the naked eye despite being a fifth magnitude star.
The brighter star of the Pleione binary pair, component A, is a hot type B star 184 times more luminous than the Sun. It is classified as Be star with certain distinguishing traits: periodic phase changes and a complex circumstellar environment composed of two gaseous disks at different angles to each other. The primary star rotates rapidly, close to its breakup velocity, even faster than Achernar. Although some research on the companion star has been performed, stellar characteristics of the orbiting B component are not well known.