In Chinese, 海石 (Hǎi Dàn), meaning Sea Rock, refers to an asterism consisting of υ Carinae, ε Carinae, ι Carinae, HD 83183 and HD 84810.[7] Consequently, υ Carinae itself is known as 海石五 (Hǎi Dàn wǔ, English: the Fifth Star of Sea Rock.)[8]
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 a O9 V star.[4] With an apparent magnitude of +3.08,[3] it has an effective temperature of about 7,600 K,[4] giving it a white hue. The companion, υ Carinae B, is a giant star with a classification of B7 III,[3] although Mandrini and Niemela (1986) suggested it may be a subgiant star with a classification of B4–5 IV.[4] 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.[4] This system is roughly 12 million years old.[5]
^ abcdNicolet, B. (1978). "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System". Astronomy and Astrophysics Supplement Series. 34: 1–49. Bibcode:1978A&AS...34....1N.
^ abcdefghijklSamedov, Z. A. (1988), "On the visual binary υ Car and the chemical composition of its brighter component", Izvestiya Krymskoj Astronomicheskoj Observatorii, 79: 57–63, Bibcode:1988IzKry..79...57S
^ abMandrini, C. H.; Niemela, V. S. (November 1986), "On the visual binary Upsilon Carinae", Monthly Notices of the Royal Astronomical Society, 223: 79–85, Bibcode:1986MNRAS.223...79M
