Tau Orionis (τ Ori, τ Orionis) is a solitary[10]star in the constellationOrion. 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.
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]
Proper names
According to Richard H. Allen, this star, along with β Eri, λ Eri and ψ Eri were Al Kursiyy al Jauzah, "the Chair (or "Footstool") of the Central One".[12] However, per the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Kursiyy al Jauzah were the title for just three stars: β Eri as Cursa, ψ Eri as Al Kursiyy al Jauzah I and λ Eri as Al Kursiyy al Jauzah II, excluding this star.[13]
In Chinese, 玉井 (Yù Jǐng), meaning Jade Well, refers to an asterism consisting of τ Orionis, β Eridani, λ Eridani and ψ Eridani.[14] Consequently, the Chinese name for τ Orionis itself is 玉井四 (Yù Jǐng sì, English: the Fourth Star of Jade Well.).[15] From this Chinese title, the name Yuh Tsing is derived.[12]
^ abcdCrawford, D. L.; et al. (1971), "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere", The Astronomical Journal, 76: 1058, Bibcode:1971AJ.....76.1058C, doi:10.1086/111220.
^Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W.