Tau_Orionis
Tau Orionis
Star in the constellation Orion
Tau Orionis (τ Ori, τ Orionis) is a solitary[10] star in the constellation Orion. If an imaginary line is drawn north-west between the stars Rigel and Mintaka, Tau Orionis can be found roughly one-sixth of the way to Mintaka. It is visible to the naked eye with an apparent visual magnitude of 3.58.[2] Based upon an annual parallax shift of 6.6 mas,[1] it is located around 490 light years from the Sun.
This is a B-type giant star with a stellar classification of B5III5 III.[3] It has around 5.4[6] times the radius of the Sun and 6.2[5] times the Sun's mass. The star shines with 933[7] times the solar luminosity from its outer atmosphere at an effective temperature of 10,829[7] K. it is around 63[5] million years old, with a peculiar velocity through space of 16.9 km/s.[5]
Tau Orionis has three visual companions: magnitude 11.0 component B at an angular separation of 33.30″ along a position angle of 251°; magnitude 10.9 component C lying some 3.80″ from component B; and magnitude 10.9 component D at 36.0″ from τ Ori along a position angle of 51°, all as of 2011.[11]