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This article is about γ Centauri. Not to be confused with Y Centauri or y Centauri.
Gamma Centauri
Location of γ Centauri (circled)
Observation data
Epoch J2000       Equinox J2000
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  mas [1]
Distance130 ± 1  ly
(39.9 ± 0.4  pc)
Absolute magnitude (MV)−0.81 [7]
Orbit [8]
Companionγ 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
Mass2.91 [9]  M☉
Surface gravity (log g)3.52 [4]  cgs
Temperature9,082 [4]  K
Metallicity−0.29 [4]
Other designations
Muhlifain, γ Cen, Gam Cen, CD−48°7597, GC 17262, HD 110304, HIP 61932, HR 4819, SAO 223603, CCDM J12415-4858, WDS 12415-4858
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  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. ^ a b c d e 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. S2CID  18759600.
  2. ^ a b c d 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. ^ a b c 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. ^ a b c d e 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. arXiv: astro-ph/0603770. Bibcode: 2006AJ....132..161G. doi: 10.1086/504637. S2CID  119476992.
  5. ^ a b 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. Bibcode: 1987ApJS...65..581G. doi: 10.1086/191237.
  6. ^ Evans, D. S. (June 20–24, 1966). Batten, Alan Henry; Heard, John Frederick (eds.). The Revision of the General Catalogue of Radial Velocities. Vol. 30. University of Toronto: International Astronomical Union. p. 57. Bibcode: 1967IAUS...30...57E. {{ cite book}}: |work= ignored ( help)
  7. ^ Schaaf, Fred (2008). The brightest stars: discovering the universe through the sky's most brilliant stars. John Wiley and Sons. p. 262. Bibcode: 2008bsdu.book.....S. ISBN  978-0-471-70410-2.
  8. ^ a b c Argyle, R. W.; et al. (May 2015). "Micrometric measures and orbits of southern visual double stars". Astronomische Nachrichten. 336 (4): 378–387. Bibcode: 2015AN....336..378A. doi: 10.1002/asna.201412166.
  9. ^ a b 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. arXiv: 1007.0425. Bibcode: 2011ApJS..192....2S. doi: 10.1088/0067-0049/192/1/2. S2CID  119226823.
  10. ^ Paul Kunitzsch (1959). Arabische Sternnamen in Europa, von Paul Kunitzsch. O. Harrassowitz. p. 188.
  11. ^ 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. Bibcode: 2001AJ....122.3466M. doi: 10.1086/323920.
  12. ^ Kaler, James B. "MUHLIFAIN (Gamma Centauri)". Stars. University of Illinois. Retrieved 2011-12-31.
  13. ^ (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.
  14. ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived January 30, 2011, at the Wayback Machine, Hong Kong Space Museum. Accessed online November 23, 2010.
  15. ^ 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
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