Eta_Lupi
Eta Lupi
Probable triple star system in the constellation of Lupus
η Lupi, often Latinised as Eta Lupi, is a probable triple star[4][12] system in the southern constellation of Lupus. It is visible to the naked eye with an apparent visual magnitude of 3.41.[2] Based upon an annual parallax shift of 27.80[1] mas as seen from Earth, it is located around 136 parsecs (440 ly) distant from the Sun. It is a member of the Upper Centaurus–Lupus subgroup of the nearby Sco OB2 association.[13]
The inner pair in this triple system has an estimated orbital period of around 27,000 years.[12] As of 2013, they had an angular separation of 15.0 arc seconds along a position angle of 19°.[3] The primary star, component A, is an evolving A-type subgiant star with a stellar classification of B2 IV.[4] It has used up the supply of hydrogen at its core and has begun to expand off the main-sequence.
The secondary, component B, is a chemically peculiar A-type main sequence star with a class of A5 Vp[4] and an estimated mass 2.10 times that of the Sun.[12] The outer member, component C, has an orbital period of around half a million years.[12] As of 2007, it had an angular separation of 115.8 arc seconds along a position angle of 248° from the primary.[3] It is an F-type main sequence star with a classification of F5 V and an estimated 1.29 times the Sun's mass.[12]