Lambda Scorpii
Lambda Scorpii is a triple star system and the second-brightest object in the constellation of Scorpius. It is formally named Shaula; Lambda Scorpii is its Bayer designation, which is Latinised from λ Scorpii and abbreviated Lambda Sco or λ Sco. With an apparent visual magnitude of 1.62, it is one of the brightest stars in the night sky.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Scorpius |
| Pronunciation | /ˈʃɔːlə/ |
| Right ascension | 17h 33m 36.520s |
| Declination | −37° 06′ 13.76″ |
| Apparent magnitude (V) | 1.62 + 14.9 + 12.0 |
| Characteristics | |
| Spectral type | B1.5IV + B2IV |
| U−B color index | −0.880 |
| B−V color index | −0.240 |
| Variable type | Beta Cephei (A) |
| Astrometry | |
| Radial velocity (Rv) | −3.00 km/s |
| Proper motion (μ) | RA: −8.90 mas/yr Dec.: −29.95 mas/yr |
| Parallax (π) | 5.71 ± 0.90 mas |
| Distance | approx. 570 ly (approx. 180 pc) |
| Absolute magnitude (MV) | −3.70 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 2.8825 yr |
| Semi-major axis (a) | 49.3 mas |
| Eccentricity (e) | 0.121 |
| Inclination (i) | 77.2° |
| Orbit | |
| Primary | Aa |
| Companion | Ab |
| Period (P) | 5.9520 d |
| Eccentricity (e) | 0.26 |
| Semi-amplitude (K1) (primary) | 39.3 km/s |
| Details | |
| λ Sco Aa | |
| Mass | 10.4 M☉ |
| Radius | 8.8±1.2 R☉ |
| Luminosity | 36,300 L☉ |
| Surface gravity (log g) | 3.8 cgs |
| Temperature | 25,000±1,000 K |
| Rotation | 3.4±0.5 d |
| Rotational velocity (v sin i) | 150 km/s |
| λ Sco B | |
| Mass | 8.1 M☉ |
| Radius | 4.7±1.0 R☉ |
| Surface gravity (log g) | 4.0 cgs |
| Temperature | 25,000±1,000 K |
| λ Sco Ab | |
| Mass | 1.8 M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
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