Atlas (star)
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 03h 49m 09.74258s |
| Declination | +24° 03′ 12.3003″ |
| Apparent magnitude (V) | 3.63 (3.84 / 5.46) |
| Characteristics | |
| Spectral type | B8III |
| U−B color index | −0.36 |
| B−V color index | −0.08 |
| Variable type | SPB |
| Astrometry | |
| Radial velocity (Rv) | 8.5±2 km/s |
| Proper motion (μ) | RA: +19.079 mas/yr Dec.: −46.193 mas/yr |
| Parallax (π) | 8.1184±0.4791 mas |
| Distance | 431 ± 13 ly (132±4 pc) |
| Absolute magnitude (MV) | −1.82 |
| Orbit | |
| Primary | Aa1 |
| Companion | Aa2 |
| Period (P) | 290.984±0.079 d |
| Semi-major axis (a) | 13.08±0.12 mas |
| Eccentricity (e) | 0.2385±0.0063 |
| Inclination (i) | 107.87±0.49° |
| Longitude of the node (Ω) | 154.0±0.7° |
| Periastron epoch (T) | JD 2450583.0±1.9 |
| Argument of periastron (ω) (secondary) | 151.9±2.2° |
| Semi-amplitude (K1) (primary) | 26.55±1.41 km/s |
| Semi-amplitude (K2) (secondary) | 36.89±0.22 km/s |
| Details | |
| Aa1 | |
| Mass | 4.74±0.25 M☉ |
| Radius | 7.9±0.8 R☉ |
| Surface gravity (log g) | 3.32±0.09 cgs |
| Temperature | 13,500±300 K |
| Rotational velocity (v sin i) | 182 km/s |
| Aa2 | |
| Mass | 3.42±0.25 M☉ |
| Radius | 3.2±0.3 R☉ |
| Surface gravity (log g) | 3.96±0.09 cgs |
| Temperature | 13,660 K |
| Ab | |
| Mass | 2.09 M☉ |
| Other designations | |
| 27 Tau, BD+23°557, FK5 142, HD 23850, HIP 17847, HR 1178, SAO 76228 | |
| Database references | |
| SIMBAD | data |
Atlas /ˈætləs/, designation 27 Tauri, is a triple star system in the constellation of Taurus. It is a member of the Pleiades, an open star cluster (M45). It is 431 light-years (132 parsecs) away, and is 3.92 degrees north of the ecliptic.