Omega Carinae
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Carina |
| Right ascension | 10h 13m 44.21739s[1] |
| Declination | –70° 02′ 16.4563″[1] |
| Apparent magnitude (V) | 3.29[2] |
| Characteristics | |
| Spectral type | B8 IIIe[3] |
| U−B color index | –0.285[4] |
| B−V color index | –0.083[4] |
| Astrometry | |
| Radial velocity (Rv) | +7.0[2] km/s |
| Proper motion (μ) | RA: -36.01[1] mas/yr Dec.: +7.09[1] mas/yr |
| Parallax (π) | 9.54 ± 0.09[1] mas |
| Distance | 342 ± 3 ly (104.8 ± 1.0 pc) |
| Details | |
| Surface gravity (log g) | 3.581[5] cgs |
| Temperature | 13,275[5] K |
| Rotational velocity (v sin i) | 245[5] km/s |
| Other designations | |
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[2] and is located at a distance of about 342 light-years (105 parsecs) from Earth.[1]
Properties
Omega Carinae has a stellar classification of B8 IIIe,[3] which places it among a category known as Be stars that display emission lines of hydrogen their spectrum. Omega Carinae is a shell star,[3] 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[5] 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.[5]
In the next 7500 years, the south Celestial pole will pass close to this stars and I Carinae (5800 CE).[7]
In culture
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 .[8] Consequently, ω Carinae itself is known as 南船四 (Nán Chuán sì, English: the Fourth Star of Southern Boat.)[9]
References
- 1 2 3 4 5 6 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 - 1 2 3 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
- 1 2 3 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
- 1 2 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
- 1 2 3 4 5 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
- ↑ http://myweb.tiscali.co.uk/moonkmft/Articles/Precession.html
- ↑ (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