Epoch J2000 Equinox J2000
|Right ascension||10h 13m 44.21739s|
|Declination||–70° 02′ 16.4563″|
|Apparent magnitude (V)||3.29|
|Spectral type||B8 IIIe|
|U−B color index||–0.285|
|B−V color index||–0.083|
|Radial velocity (Rv)||+7.0 km/s|
|Proper motion (μ)||RA: -36.01 mas/yr
Dec.: +7.09 mas/yr
|Parallax (π)||9.54 ± 0.09 mas|
|Distance||342 ± 3 ly
(104.8 ± 1.0 pc)
|Surface gravity (log g)||3.581 cgs|
|Rotational velocity (v sin i)||245 km/s|
Omega Carinae (ω Car, ω Carinae) is a star in the constellation Carina. With a declination greater than 70 degrees south of the celestial equator, it is the most southerly of the bright stars of Carina (third-magnitude or brighter), and it is part of a southern asterism known as the Diamond Cross. This star has an apparent visual magnitude of 3.3 and is located at a distance of about 342 light-years (105 parsecs) from Earth.
Omega Carinae has a stellar classification of B8 IIIe, which places it among a category known as Be stars that display emission lines of hydrogen their spectrum. Omega Carinae is a shell star, having a circumstellar disk of gas surrounding its equator. The luminosity class of III indicates it has evolved into a giant star, having exhausted the hydrogen at its core and left the main sequence. The effective temperature of 13,275 K in its outer envelope is what gives this star the blue-white hue that is characteristic of B-type stars.
This star is rotating rapidly with a projected rotational velocity of 245 km s−1, which gives a lower limit to the star's azimuthal velocity along the equator. The critical equatorial velocity, at which the star would begin to break up, is 320 km s−1. The star's axis of rotation is inclined by an estimated angle of 70.8° to the line of sight from the Earth.
In Chinese, 南船 (Nán Chuán), meaning Southern Boat, refers to an asterism consisting of ω Carinae, V337 Carinae, PP Carinae, θ Carinae and β Carinae . Consequently, ω Carinae itself is known as 南船四 (Nán Chuán sì, English: the Fourth Star of Southern Boat.)
Rarely, this star is called by the name Simiram.
- 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
- Wielen, R. et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions (35), Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W
- Rivinius, Th.; Štefl, S.; Baade, D. (November 2006), "Bright Be-shell stars", Astronomy and Astrophysics 459 (1): 137–145, Bibcode:2006A&A...459..137R, doi:10.1051/0004-6361:20053008
- Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168
- Frémat, Y. et al. (September 2005), "Effects of gravitational darkening on the determination of fundamental parameters in fast-rotating B-type stars", Astronomy and Astrophysics 440 (1): 305–320, arXiv:astro-ph/0503381, Bibcode:2005A&A...440..305F, doi:10.1051/0004-6361:20042229
- "ome Car -- Be Star", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2012-01-13
- (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.
- (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 28 日