Gamma Centauri

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
SIMBADdata

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]

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  2. ^ a b c d Cite error: The named reference clpl4_99 was invoked but never defined (see the help page).
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  4. ^ a b c d e Cite error: The named reference aj132_1_161 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Gray_Garrison_1987 was invoked but never defined (see the help page).
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  8. ^ a b c Cite error: The named reference Argyle_et_al_2015 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference apjs192_1_2 was invoked but never defined (see the help page).
  10. ^ Paul Kunitzsch (1959). Arabische Sternnamen in Europa, von Paul Kunitzsch. O. Harrassowitz. p. 188.
  11. ^ Cite error: The named reference aj122_6_3466 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference kaler was invoked but never defined (see the help page).