Astronomy:Gamma Centauri
  | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 12h 41m 31.04008s[1] |
| Declination | −48° 57′ 35.5375″[1] |
| Apparent magnitude (V) | +2.17[2] (+2.85/+2.95)[3] |
| Characteristics | |
| Spectral type | A1IV+[4] (A1IV + A0IV)[5] |
| U−B color index | −0.01[2] |
| B−V color index | −0.01[2] |
| Astrometry | |
| Radial velocity (Rv) | −5.5[6] km/s |
| Proper motion (μ) | RA: −185.72[1] mas/yr Dec.: +5.79[1] mas/yr |
| Parallax (π) | 25.06 ± 0.28[1] mas |
| Distance | 130 ± 1 ly (39.9 ± 0.4 pc) |
| Absolute magnitude (MV) | −0.81[7] |
| Orbit[8] | |
| Companion | γ Centauri B |
| Period (P) | 83.57±0.21 yr |
| Semi-major axis (a) | 0.869±0.011″ |
| Eccentricity (e) | 0.793±0.003 |
| Inclination (i) | 113.7±0.7° |
| Longitude of the node (Ω) | 2.6±0.7° |
| Periastron epoch (T) | 1,931.25 ± 0.07 |
| Argument of periastron (ω) (secondary) | 187.9±1.5° |
| Details | |
| Mass | 2.91[9] M☉ |
| Surface gravity (log g) | 3.52[4] cgs |
| Temperature | 9,082[4] K |
| Metallicity | −0.29[4] |
| Other designations | |
| Database references | |
| SIMBAD | data |
Gamma Centauri, Latinized from γ Centauri, is a binary star system in the southern constellation of Centaurus. It has the proper name Muhlifain,[10] not to be confused with Muliphein, which is γ Canis Majoris; both names derive from the same Arabic root. The system is visible to the naked eye as a single point of light with a combined apparent visual magnitude of +2.17;[2] individually they are third-magnitude stars.[3]
This system is located at a distance of about 130 light-years (40 parsecs) from the Sun based on parallax. In 2000, the pair had an angular separation of 1.217 arcseconds with a position angle of 351.9°.[3] Their positions have been observed since 1897, which is long enough to estimate an orbital period of 84.5 years and a semimajor axis of 0.93 arcsecond.[11][8] At the distance of this system, this is equivalent to a physical separation of about 93 astronomical unit|AU.[12]
The combined stellar classification of the pair is A1IV+;[4] when they are separated out they have individual classes of A1IV and A0IV,[5] suggesting they are A-type subgiant stars in the process of becoming giants. The star Tau Centauri is relatively close to Gamma Centauri, with an estimated separation of 1.72 light-years (0.53 parsecs).[9] There is a 98% chance that they are co-moving stars.[8]
Etymology
In Chinese astronomy, 庫樓 (Kù Lóu), meaning Arsenal, refers to an asterism consisting of γ Centauri, ζ Centauri, η Centauri, θ Centauri, 2 Centauri, HD 117440, ξ1 Centauri, τ Centauri, D Centauri and σ Centauri.[13] Consequently, the Chinese name for γ Centauri itself is 庫樓七 (Kù Lóu qī, English: the Seventh Star of Arsenal).[14]
The people of Aranda and Luritja tribe around Hermannsburg, Central Australia named a quadrangular arrangement comprising this star, δ Cen (Ma Wei), δ Cru (Imai) and γ Cru (Gacrux) as Iritjinga ("The Eagle-hawk").[15]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Johnson, H. L. et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory 4 (99): 99. Bibcode: 1966CoLPL...4...99J.
- ↑ 3.0 3.1 3.2 Fabricius, C.; Makarov, V. V. (April 2000). "Two-colour photometry for 9473 components of close Hipparcos double and multiple stars". Astronomy and Astrophysics 356: 141–145. Bibcode: 2000A&A...356..141F.
- ↑ 4.0 4.1 4.2 4.3 4.4 Gray, R. O. et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal 132 (1): 161–170. doi:10.1086/504637. Bibcode: 2006AJ....132..161G.
- ↑ 5.0 5.1 Gray, R. O.; Garrison, R. F. (December 1987). "The Early A-Type Stars: Refined MK Classification, Confrontation with Stroemgren Photometry, and the Effects of Rotation". Astrophysical Journal Supplement 65: 581. doi:10.1086/191237. Bibcode: 1987ApJS...65..581G.
- ↑ Evans, D. S. (June 20–24, 1966). The Revision of the General Catalogue of Radial Velocities. 30. University of Toronto: International Astronomical Union. p. 57. Bibcode: 1967IAUS...30...57E.
- ↑ Schaaf, Fred (2008). The brightest stars: discovering the universe through the sky's most brilliant stars. John Wiley and Sons. p. 262. ISBN 978-0-471-70410-2. Bibcode: 2008bsdu.book.....S.
- ↑ 8.0 8.1 8.2 Argyle, R. W. et al. (May 2015). "Micrometric measures and orbits of southern visual double stars". Astronomische Nachrichten 336 (4): 378–387. doi:10.1002/asna.201412166. Bibcode: 2015AN....336..378A.
- ↑ 9.0 9.1 Shaya, Ed J.; Olling, Rob P. (January 2011). "Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue". The Astrophysical Journal Supplement 192 (1): 2. doi:10.1088/0067-0049/192/1/2. Bibcode: 2011ApJS..192....2S.
- ↑ Paul Kunitzsch (1959). Arabische Sternnamen in Europa, von Paul Kunitzsch. O. Harrassowitz. p. 188. https://books.google.com/books?id=qhtGQwAACAAJ.
- ↑ Mason, Brian D. et al. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal 122 (6): 3466–3471. doi:10.1086/323920. Bibcode: 2001AJ....122.3466M.
- ↑ Kaler, James B.. "MUHLIFAIN (Gamma Centauri)". Stars. University of Illinois. http://stars.astro.illinois.edu/sow/muhlifain.html.
- ↑ (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.
- ↑ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 , Hong Kong Space Museum. Accessed online November 23, 2010.
- ↑ Raymond Haynes; Roslynn D. Haynes; David Malin; Richard McGee (1996), Explorers of the Southern Sky: A History of Australian Astronomy, Cambridge: Cambridge University Press, p. 8, ISBN 978-0-521-36575-8, https://books.google.com/books?id=XoeiJxMmXZ8C
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