Lambda Lupi

Lambda Lupi, Latinized from λ Lupi, is a triple star^[11] system in the southern constellation of Lupus. It is visible to the naked eye with a combined apparent visual magnitude of 4.04.^[2] Based upon an annual parallax shift of just 4.20^[1] mas as seen from Earth, it is located roughly 800 light years from the Sun. The system has a peculiar velocity of 27.4±4.9 km/s relative to its neighbors, making it a candidate runaway star system.^[9] It is a member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus OB association.^[12]

Lambda Lupi

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Lupus
Right ascension	15h 08m 50.61639s[1]
Declination	−45° 16′ 47.4950″[1]
Apparent magnitude (V)	4.04[2] (4.43 + 5.23)[3]
Characteristics
Spectral type	B3 V[4] (B3 V + B3 V)[5]
U−B color index	−0.67[2]
B−V color index	−0.18[2]
Astrometry
Radial velocity (Rv)	+9.80±1.78[6] km/s
Proper motion (μ)	RA: −15.88[1] mas/yr Dec.: −26.80[1] mas/yr
Parallax (π)	4.20±0.66 mas[1]
Distance	approx. 800 ly (approx. 240 pc)
Absolute magnitude (MV)	−2.75[7]
Orbit[8]
Period (P)	70.8±0.8 yr
Semi-major axis (a)	0.2597±0.0021″
Eccentricity (e)	0.6283±0.0090
Inclination (i)	71.59±0.41°
Longitude of the node (Ω)	26.64±0.61°
Periastron epoch (T)	1997.907 ± 0.105
Argument of periastron (ω) (secondary)	299.9±1.1°
Details
λ Lup A
Mass	8.14[8] M☉
Rotational velocity (v sin i)	135 km/s
Age	28.1±4.1[9] Myr
λ Lup B
Mass	5.84 M☉
Other designations
λ Lup, CD−44°9889, HD 133955, HIP 74117, HR 5626, SAO 225483, WDS J15088-4517AB[10]
Database references
SIMBAD	data

The two visible components of this system orbit each other over a period of 70.8 years with a large eccentricity of 0.63.^[8] The primary component has a visual magnitude of 4.43, while the secondary is of magnitude 5.23.^[3] Both are B-type main sequence stars with a stellar classification of B3 V.^[5] One of the pair is itself a double-lined spectroscopic binary, making this a triple star system.^[11]