Upsilon Carinae
Upsilon Carinae is a double star in the southern constellation of Carina. Its name is a Bayer designation that is Latinized from υ Carinae, and abbreviated Upsilon Car or υ Car. This pair is part of the Diamond Cross asterism in southern Carina. The Upsilon Carinae system has a combined apparent magnitude of +2.97 and is approximately 1,400 light years from Earth. It is drifting further away with a line of sight velocity of +14 km/s.
In Chinese, 海石, meaning Sea Rock, refers to an asterism consisting of υ Carinae, ε Carinae, ι Carinae, HD 83183 and HD 84810. Consequently, υ Carinae itself is known as 海石五
In the next 7500 years, the south Celestial pole will pass close to these stars and Iota Carinae.
Properties
The primary component, υ Carinae A, has a stellar classification of A8 Ib, making it a supergiant star that has exhausted the hydrogen at its core and evolved away from its brief main sequence lifetime as an B-type star. With an apparent magnitude of +3.08, it has an effective temperature of about 7,500 K, giving it a white hue. The companion, υ Carinae B, is a giant star with a classification of B7 III, although Mandrini and Niemela suggested it may be a subgiant star with a classification of B4–5 IV. The outer envelope of this star has an effective temperature of around 23,000 K, resulting in the blue-white hue of a B-type star.The two stars have an angular separation of 5.030 arcseconds. As a binary star system, they would have an estimated orbital period of at least 19,500 years and a present-day separation of around 2,000 Astronomical Units. This system is roughly 12 million years old.