Alpha Centauri (α Centauri, abbreviatit Alf Cen, α Cen) is the closest starn seestem tae the Solar Seestem, bein 4.37 light-years (1.34 pc) frae the Sun.

Alpha Centauri
Alpha, Beta and Proxima Centauri (1).jpg
α Centauri AB is the bricht starn tae the left, wi Proxima Centauri circled in reid. The bricht starn tae the richt is β Centauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Alpha Centauri A
Richt ascension 14h 39m 36.49400s[1]
Declination –60° 50′ 02.3737″[1]
Apparent magnitude (V) +0.01[2]
Alpha Centauri B
Richt ascension 14h 39m 35.06311s[1]
Declination –60° 50′ 15.0992″[1]
Apparent magnitude (V) +1.33[2]
Spectral type G2V[3]
U−B colour index +0.24[2]
B−V colour index +0.71[2]
Spectral teep K1V[3]
U−B colour index +0.68[2]
B−V colour index +0.88[2]
Radial velocity (Rv)−21.4±0.76[4] km/s
Proper motion (μ) RA: −3679.25[1] mas/yr
Dec.: 473.67[1] mas/yr
Parallax (π)754.81 ± 4.11[1] mas
Distance4.37[5] ly
Absolute magnitude (MV)4.38[6]
Radial velocity (Rv)−18.6±1.64[4] km/s
Proper motion (μ) RA: −3614.39[1] mas/yr
Dec.: 802.98[1] mas/yr
Parallax (π)754.81 ± 4.11[1] mas
Distance4.37[5] ly
Absolute magnitude (MV)5.71[6]
Alpha Centauri A
Mass1.100[7] M
Radius1.2234±0.0053[8] R
Luminosity1.519[7] L
Surface gravity (log g)4.30[9] cgs
Temperatur5,790[7] K
Metallicity [Fe/H]0.20[7] dex
Rotation22[10] days
Age≈4.4[11] Gyr
Alpha Centauri B
Mass0.907[7] M
Radius0.8632±0.0037[8] R
Luminosity0.5002[7] L
Surface gravity (log g)4.37[9] cgs
Temperatur5,260[7] K
Rotation41[10] days
Age≈6.5[11] Gyr
Period (P)79.91±0.011 yr
Semi-major axis (a)17.57±0.022
Eccentricity (e)0.5179±0.00076
Inclination (i)79.205±0.041°
Longitude o the node (Ω)204.85±0.084°
Periastron epoch (T)1875.66±0.012
Argument o periastron (ω)
Ither designations
Toliman, Bungula, Gliese 559, FK5 538, CD−60°5483, CCDM J14396-6050, GC 19728
α Cen A: Rigil Kentaurus, Rigil Kent, α1 Centauri, HR 5459, HD 128620, GCTP 3309.00, LHS 50, SAO 252838, HIP 71683
α Cen B: α2 Centauri, HR 5460, HD 128621, LHS 51, HIP 71681
Database references
Exoplanet Archivedata
Extrasolar Planets


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
  3. 3.0 3.1 Torres, C. A. O.; Quast, G. R.; da Silva, L .; de la Reza, R.; Melo, C. H. F.; Sterzik, M. (2006). "Search for associations containing young stars (SACY)". Astronomy and Astrophysics. 460 (3): 695–708. arXiv:astro-ph/0609258. Bibcode:2006A&A...460..695T. doi:10.1051/0004-6361:20065602. ISSN 0004-6361.
  4. 4.0 4.1 Valenti, Jeff A.; Fischer, Debra A. (2005). "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs". The Astrophysical Journal Supplement Series. 159 (1): 141–166. Bibcode:2005ApJS..159..141V. doi:10.1086/430500. ISSN 0067-0049.
  5. 5.0 5.1 Wilkinson, John (2012). "The Sun and Stars". New Eyes on the Sun. Astronomers' Universe. pp. 219–236. doi:10.1007/978-3-642-22839-1_10. ISBN 978-3-642-22838-4. ISSN 1614-659X.
  6. 6.0 6.1 P. A. Wiegert; M. J. Holman (1997). "The stability of planets in the Alpha Centauri system". The Astronomical Journal. 113: 1445&nbsp, – 1450. arXiv:astro-ph/9609106. Bibcode:1997AJ....113.1445W. doi:10.1086/118360.
  7. 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 Thévenin, F.; Provost, J.; Morel, P.; Berthomieu, G.; Bouchy, F.; Carrier, F. (2002). "Asteroseismology and calibration of alpha Cen binary system". Astronomy & Astrophysics. 392: L9. arXiv:astro-ph/0206283. Bibcode:2002A&A...392L...9T. doi:10.1051/0004-6361:20021074.
  8. 8.0 8.1 Kervella, P.; Bigot, L.; Gallenne, A.; Thévenin, F. (January 2017). "The radii and limb darkenings of α Centauri A and B. Interferometric measurements with VLTI/PIONIER". Astronomy & Astrophysics. 597. A137. arXiv:1610.06185. Bibcode:2017A&A...597A.137K. doi:10.1051/0004-6361/201629505.
  9. 9.0 9.1 Gilli G.; Israelian G.; Ecuvillon A.; Santos N. C.; Mayor M. (2006). "Abundances of Refractory Elements in the Atmospheres of Stars with Extrasolar Planets". Astronomy and Astrophysics. 449 (2): 723–36. arXiv:astro-ph/0512219. Bibcode:2006A&A...449..723G. doi:10.1051/0004-6361:20053850. libcode
  10. 10.0 10.1 Kervella, P.; Thévenin, F.; Ségransan, D.; Berthomieu, G.; Lopez, B.; Morel, P.; Provost, J. (2003). "The diameters of α Centauri A and B". Astronomy and Astrophysics. 404 (3): 1087–1097. arXiv:astro-ph/0303634. Bibcode:2003A&A...404.1087K. doi:10.1051/0004-6361:20030570. ISSN 0004-6361.
  11. 11.0 11.1 E. E. Mamajek; L. A. Hillenbrand (2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785.
  12. Pourbaix, D.; et al. (2002). "Constraining the difference in convective blueshift between the components of alpha Centauri with precise radial velocities". Astronomy and Astrophysics. 386 (1): 280–85. arXiv:astro-ph/0202400. Bibcode:2002A&A...386..280P. doi:10.1051/0004-6361:20020287.

Coordinates:   14h 39m 36.4951s, −60° 50′ 02.308″