Gamma Centauri

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This article is about γ Centauri. For HD 127233, see Y Centauri. For y Centauri, see HD 120987.
Gamma Centauri A/B
Diagram showing star positions and boundaries of the Centauri constellation and its surroundings
Cercle rouge 100%.svg

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] (A0III/A0III)[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[5]
Details
Mass 2.91[7] M
Surface gravity (log g) 3.52[4] cgs
Temperature 9,082[4] K
Orbit[8]
Companion γ Centauri B
Period (P) 84.5 yr
Semi-major axis (a) 0.93"
Other designations
Muhlifain, HR 4819, HD 110304, CD−48°7597, SAO 223603, WDS 12415-4858, HIP 61932, GC 17262, CCDM J12415-4858.
Database references
SIMBAD data

Gamma Centauri (γ Cen, γ Centauri) is a star in the southern constellation Centaurus. It has the proper name Muhlifain,[9] not to be confused with Muliphein, which is γ Canis Majoris; both names derive from the same Arabic root.

Gamma Centauri is a double star located about 130 light-years (40 parsecs) from Earth. The combined apparent visual magnitude of the pair is +2.17,[2] although individually they are third magnitude stars.[3] The stellar classification of the pair is A1IV+,[4] suggesting they are A-type subgiant stars in the process of becoming giants. Individually, their stellar classifications are sometimes listed as A0III, which would mean they have already become giants.[5]

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 arcseconds.[8] At the distance of this system, this is equivalent to a linear distance of about 93 Astronomical Units.[10] The star Tau Centauri is relatively close to Gamma Centauri, with an estimated separation of 1.72 light-years (0.53 pc).[7]

Etymology[edit]

In Chinese, 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.[11] Consequently, γ Centauri itself is known as 庫樓七 (Kù Lóu qī, English: the Seventh Star of Arsenal.)[12]

The people of Aranda and Luritja tribe around Hermannsburg, Central Australia named Iritjinga, "The Eagle-hawk", a quadrangular arrangement comprising this star, δ Cen (Ma Wei), δ Cru (Palida) and γ Cru (Gacrux), .[13]

References[edit]

  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. 
  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). 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 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 
  5. ^ a b c Schaaf, Fred (2008), The brightest stars: discovering the universe through the sky's most brilliant stars, John Wiley and Sons, p. 262, ISBN 0-471-70410-5 
  6. ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, retrieved 2009-09-10 
  7. ^ 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 
  8. ^ a b 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 
  9. ^ Kunitzsch, P., Arabische Sternnamen in Europa, Otto Harrassowitz, Wiesbaden, p.188.
  10. ^ Kaler, James B., "MUHLIFAIN (Gamma Centauri)", Stars (University of Illinois), retrieved 2011-12-31 
  11. ^ (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.
  12. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  13. ^ p. 8, Explorers of the southern sky: a history of Australian astronomy, Raymond Haynes, Cambridge, Cambridge University Press, 1996.