Nu_Orionis
Nu Orionis
Binary star system in the constellation Orion
Nu Orionis (ν Orionis) is a binary star[11] system in the northeastern part of the constellation Orion. It should not be confused with the variable star NU Orionis.[12] Nu Orionis has an apparent visual magnitude of 4.42,[2] which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 0.00632 arcseconds,[1] the distance to this system is roughly 520 light years.
This is a single-lined spectroscopic binary system,[9] which means that only the absorption line features of one of the components can be distinguished. The components orbit each other with a period of 131.2 days and an eccentricity of 0.64.[6] Depending on the source, the primary is either a B-type main sequence star with a stellar classification of B3 V,[3] or a more evolved B-type subgiant star of class B3 IV.[4] It has an angular diameter of 0.251 mas,[13] which, at the estimated distance of this system, yields a physical size of about 4.3 times the radius of the Sun.[7] The mass is 6.7[4] times that of the Sun and it shines with 1,965[3] times the solar luminosity from its outer atmosphere at an effective temperature of 17,880 K.[8]