Lambda Scorpii

Lambda Scorpii is a triple star system and the second-brightest object in the constellation of Scorpius. It is also called Shaula. Lambda Scorpii is its Bayer designation, which is translated 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.

λ Scorpii

Location of λ Scorpii (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Scorpius
Pronunciation	/ˈʃɔːlə/[1][2]
Right ascension	17h 33m 36.520s[3]
Declination	−37° 06′ 13.76″[3]
Apparent magnitude (V)	1.62 + 14.9 + 12.0[3][4]
Characteristics
Spectral type	B1.5IV + B2IV[5][6]
U−B color index	−0.880[7]
B−V color index	−0.240[7]
Variable type	Beta Cephei (A)[8]
Astrometry
Radial velocity (Rv)	−3.00[9] km/s
Proper motion (μ)	RA: −8.90[3][3] mas/yr Dec.: −29.95[3] mas/yr
Parallax (π)	5.71 ± 0.90[3] mas
Distance	approx. 570 ly (approx. 180 pc)
Absolute magnitude (MV)	−3.70[10]
Orbit[11]
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[11]
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[5] M☉
Radius	8.8±1.2[8] R☉
Luminosity	36,300[8] L☉
Surface gravity (log g)	3.8[6] cgs
Temperature	25,000±1,000[8] K
Rotation	3.4±0.5 d[8]
Rotational velocity (v sin i)	150[8] km/s
λ Sco B
Mass	8.1[5] M☉
Radius	4.7±1.0[8] R☉
Surface gravity (log g)	4.0[6] cgs
Temperature	25,000±1,000[8] K
λ Sco Ab
Mass	1.8[5] M☉
Other designations
Shaula, 35 Scorpii, 35 Sco, CD−37 11673, FK5 652, HD 158926, HIP 85927, HR 6527, SAO 208954, CCDM J17336-3706A/B/C
Database references
SIMBAD	data