Upsilon Carinae

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Upsilon Carinae A/B
Diagram showing star positions and boundaries of the Carina constellation and its surroundings
Cercle rouge 100%.svg

Location of υ Carinae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Carina
Right ascension 09h 47m 06.12170s[1]
Declination –65° 04′ 19.2267″[1]
Apparent magnitude (V) 2.97[2] (+3.08/+6.25[3])
Spectral type A8 Ib + B7 III[4]
U−B color index +0.13[2]
B−V color index +0.27[2]
Radial velocity (Rv) +14[4] km/s
Proper motion (μ) RA: –11.51[1] mas/yr
Dec.: +4.71[1] mas/yr
Parallax (π) 2.27 ± 0.28[1] mas
Distance approx. 1,400 ly
(approx. 440 pc)
Absolute magnitude (MV) −5.56
υ Car A
Mass 13[4] M
Surface gravity (log g) 1.1 ± 0.3[4] cgs
Temperature 7,600 ± 350[4] K
Age 1.2 × 107[5] years
υ Car B
Mass 8[4] M
Surface gravity (log g) 3.3 ± 0.1[4] cgs
Temperature 23,000 ± 1600[4] K
Other designations
CP−64°1084 AB, HIP 48002.[6]
A: υ Car A, HD 85124, HR 3891, SAO 250696.[6]
B: υ Car B, HD 85123, HR 3890, SAO 250695.[6]
Database references
SIMBAD system

Upsilon Carinae (υ Car, υ Carinae) is a double star in the southern constellation of Carina. It is part of the Diamond Cross asterism in southern Carina. The Upsilon Carinae system has a combined apparent magnitude of +2.97[2] and is approximately 1,400 light years (440 parsecs) from Earth.[1]

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 an 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]

In the next 7500 years, the south Celestial pole will pass close to this stars and Iota Carinae (8100 CE).[9]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357 
  2. ^ a b c d Nicolet, 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. 
  3. ^ a b c Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, Bibcode:2008MNRAS.389..869E, arXiv:0806.2878Freely accessible, doi:10.1111/j.1365-2966.2008.13596.x 
  4. ^ a b c d e f g h i j k l Samedov, 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 
  5. ^ a b Mandrini, 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, doi:10.1093/mnras/223.1.79 
  6. ^ a b c "CCDM J09471-6504AB -- Double or multiple star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2012-01-26. 
  7. ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
  8. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 28 日
  9. ^

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