Omega%20Ursae%20Majoris
Omega Ursae Majoris
Binary system in the constellation Ursa Major
Omega Ursae Majoris (Omega UMa, ω Ursae Majoris, ω UMa) is the Bayer designation for a binary star system in the northern circumpolar constellation of Ursa Major. It is visible to the naked eye with an apparent visual magnitude of 4.61.[2] Based upon an annual parallax shift of 13.24 mas,[1] it is roughly 246 light years from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction factor of 0.11 due to interstellar dust.[6]
This is a single-lined spectroscopic binary star system with an orbital period of 15.8 days and an eccentricity of 0.31.[7] The primary member, component A, is an A-type main sequence star with a stellar classification of A1VsSi:.[3] The stellar spectrum has the appearance of a hot Am star, showing overabundances of many iron-peak and heavier elements, but an underabundance of helium.[12] In particular, it has an abnormal abundance of silicon.[13]