Upsilon Carinae

Upsilon Carinae, Latinized from 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]

υ Carinae
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])
Characteristics
Spectral type A8 Ib + B7 III[4]
U−B color index +0.13[2]
B−V color index +0.27[2]
Astrometry
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
Distanceapprox. 1,400 ly
(approx. 440 pc)
Absolute magnitude (MV)−5.26[5]
Details
υ Car A
Mass13[4] M☉
Surface gravity (log g)1.1 ± 0.3[4] cgs
Temperature7,600 ± 350[4] K
Age12[6] Myr
υ Car B
Mass8[4] M☉
Surface gravity (log g)3.3 ± 0.1[4] cgs
Temperature23,000 ± 1600[4] K
Other designations
υ Car, CP−64°1084, HIP 48002[7]
A: HD 85124, HR 3891, SAO 250696
B: HD 85123, HR 3890, SAO 250695
Database references
SIMBADsystem
A
B

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.[8] Consequently, υ Carinae itself is known as 海石五 (Hǎi Dàn wǔ, English: the Fifth Star of Sea Rock.)[9]

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.[6]

In the next 7500 years, the south Celestial pole will pass close to this stars and Iota Carinae (8100 CE).[10]

References
  1. van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357
  2. 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. 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x
  4. 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. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  6. 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
  7. "CCDM J09471-6504AB -- Double or multiple star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2012-01-26.
  8. (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.
  9. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 28 日
  10. http://moonkmft.co.uk/Precession.html
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