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Gamma Centauri

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This article is about γがんま Centauri. Not to be confused with Y Centauri or y Centauri.
Gamma Centauri
Location of γがんま 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みゅー) RA: −185.72[1] mas/yr
Dec.: +5.79[1] mas/yr
Parallax (πぱい)25.06 ± 0.28 mas[1]
Distance130 ± 1 ly
(39.9 ± 0.4 pc)
Absolute magnitude (MV)−0.81[7]
Orbit[8]
Companionγがんま 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おめが)2.6±0.7°
Periastron epoch (T)1,931.25 ± 0.07
Argument of periastron (ωおめが)
(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がんま Cen, Gam Cen, CD−48°7597, GC 17262, HD 110304, HIP 61932, HR 4819, SAO 223603, CCDM J12415-4858, WDS 12415-4858
Database references
SIMBADdata

Gamma Centauri, Latinized from γがんま 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がんま 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えーゆー.[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[edit]

In Chinese astronomy, 庫くら樓ろう (Kù Lóu), meaning Arsenal, refers to an asterism consisting of γがんま Centauri, ζぜーた Centauri, ηいーた Centauri, θしーた Centauri, 2 Centauri, HD 117440, ξくしー1 Centauri, τたう Centauri, D Centauri and σしぐま Centauri.[13] Consequently, the Chinese name for γがんま Centauri itself is 庫くら樓ろう七なな (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でるた Cen (Ma Wei), δでるた Cru (Imai) and γがんま Cru (Gacrux) as Iritjinga ("The Eagle-hawk").[15]

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. 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) 中國ちゅうごく星座せいざ神話しんわ, written by 陳ひね久金ひさがね. Published by 台灣たいわん書房しょぼう出版しゅっぱん有限ゆうげん公司こうし, 2005, ISBN 978-986-7332-25-7.
  14. ^ (in Chinese) 香港ほんこん太たい空そら館かん - 研究けんきゅう資源しげん - 亮あきら星ほし中ちゅう英えい對照たいしょう表ひょう 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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