Atlas (star)
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Taurus |
| Right ascension | 03h 49m 09.74306s |
| Declination | +24° 03′ 12.3017″ |
| Apparent magnitude (V) | 3.63 (3.84 / 5.46) |
| Characteristics | |
| Evolutionary stage | main sequence + main sequence |
| 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 | 444.2 ± 4.6 ly (136.2±1.4 pc) |
| Absolute magnitude (MV) | −1.82 |
| Orbit | |
| Primary | Aa1 |
| Name | Aa2 |
| Period (P) | 290.9919±0.0028 d |
| Semi-major axis (a) | 1.768±0.018 au |
| Eccentricity (e) | 0.23565±0.00011 |
| Inclination (i) | 107.863±0.032° |
| Longitude of the node (Ω) | 334.202±0.025° |
| Periastron epoch (T) | BJD 2450585.988±0.096 |
| Argument of periastron (ω) (secondary) | 335.697±0.082° |
| Semi-amplitude (K1) (primary) | 27.09±0.40 km/s |
| Semi-amplitude (K2) (secondary) | 37.63±0.53 km/s |
| Details | |
| Aa1 | |
| Mass | 5.04±0.17 M☉ |
| Radius | 7.81±0.18 (equatorial) 6.48±0.50 (polar) R☉ |
| Luminosity | 1,260 L☉ |
| Surface gravity (log g) | 3.38±0.07 cgs |
| Temperature | 12,525±200 K |
| Rotational velocity (v sin i) | 217±9 km/s |
| Aa2 | |
| Mass | 3.64±0.12 M☉ |
| Radius | 3.2±0.3 R☉ |
| Luminosity | 250 L☉ |
| Surface gravity (log g) | 4.20±0.15 cgs |
| Temperature | 12,835±450 K |
| Rotational velocity (v sin i) | 47±7 km/s |
| Other designations | |
| Atlas, 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 binary star system in the constellation of Taurus. It is a member of the Pleiades, an open star cluster (M45). It is 444 light-years (136 parsecs) away, and is 3.92 degrees north of the ecliptic.