Ξ_Serpentis
Xi Serpentis
Triple star system in the constellation Serpens
Xi Serpentis, Latinized from ξ Serpentis, is a triple star[10] system in the Serpens Cauda (tail) section of the equatorial constellation Serpens. Based upon an annual parallax shift of 30.98 mas as seen from Earth,[1] it is located 105.3 light years from the Sun. The star system is visible to the naked eye with a base apparent visual magnitude of +3.54.[2] It is moving closer to the Sun and will make perihelion passage at a distance of 27 ly (8.2 pc) in around 690,000 years.[12]
The inner pair form a single-lined spectroscopic binary with an orbital period of 2.29 days following a circular orbit with an eccentricity of 0.00.[6] The primary, component Aa, has a visual magnitude of 3.54.[13] It is a white-hued G-type giant star with a stellar classification of A9 IIIp Sr.[3] This indicates it is a chemically peculiar Ap star with an abnormal abundance of strontium. The primary has around double[7] the mass of the Sun, while its close companion, component Ab,[13] has only 18%[10] of the Sun's mass.
The third member, component B, is a magnitude 13.0[13] common proper motion companion.[10] As of 2012, it was located at an angular separation of 24 arc seconds along a position angle of 78° from the inner pair.[13] It has about 27% of the Sun's mass and an estimated orbital period of 14,763 years.[10]