1 Centauri

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1 Centauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Right ascension  13h 45m 41.24482s[1]
Declination −33° 02′ 37.3997″[1]
Apparent magnitude (V) +4.23[2]
Spectral type F2 V[3]
U−B color index +0.00[4]
B−V color index +0.38[4]
Radial velocity (Rv)−21.5±0.6[5] km/s
Proper motion (μ) RA: −462.49±0.18[1] mas/yr
Dec.: −146.49±0.16[1] mas/yr
Parallax (π)51.54 ± 0.19[1] mas
Distance63.3 ± 0.2 ly
(19.40 ± 0.07 pc)
Absolute magnitude (MV)+2.81[6]
Period (P)9.94480±0.00441 d
Eccentricity (e)0.247±0.105
Periastron epoch (T)2422737.382 ± 3.35 JD
Argument of periastron (ω)
Semi-amplitude (K1)
6.00±0.75 km/s
Mass1.35[6] M
Luminosity (bolometric)5.857[8] L
Surface gravity (log g)4.25±0.14[9] cgs
Temperature6,898±235[9] K
Metallicity [Fe/H]−0.09[8] dex
Rotational velocity (v sin i)86[6] km/s
Age1.193[9] Gyr
Other designations
i Centauri, 1 Centauri, CD−32° 9603, FK5 506, GC 18593, GJ 525.1, HD 119756, HIP 67153, HR 5168, SAO 204812[10]
Database references

1 Centauri, or i Centauri,[10] is a yellow-white hued binary star[7] system in the southern constellation Centaurus. It can be seen with the naked eye, having an apparent visual magnitude of +4.23.[2] Based upon an annual parallax shift of 51.54 mas as seen from Earth's orbit, it is located 51.5 light years from the Sun. The system is moving closer to the Sun with a radial velocity of −21.5 km/s.[5]

Spectrographic images taken at the Cape Observatory between 1921 and 1923 showed this star has a variable radial velocity, which indicated this is a single-lined spectroscopic binary star system. The pair have an orbital period of 9.94 days and an eccentricity of about 0.2.[7]

The primary component has received a number of different stellar classifications. For example, Jaschek et al. (1964) lists F0V, F2III, F4III, and F4IV, thus ranging in evolutionary state from an ordinary F-type main-sequence star to a giant star.[11] More recently, Houk (1982) listed a class of F3 V,[12] matching an ordinary main-sequence star that is generating energy through hydrogen fusion at its core. The NStars project gives it a classification of F2 V.[3]


  1. ^ a b c d e van Leeuwen, F. (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. Vizier catalog entry
  2. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015.
  3. ^ a b Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample", The Astronomical Journal, 132: 161, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
  4. ^ a b Hoffleit, Dorrit; Jaschek, Carlos (1991). The Bright star catalogue. New Haven. Bibcode:1991bsc..book.....H.
  5. ^ a b de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. ^ a b c Pizzolato, N.; et al. (September 2000), "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases", Astronomy and Astrophysics, 361: 614–628, Bibcode:2000A&A...361..614P
  7. ^ a b c Spencer Jones, Harold (1928), "Radial velocity determinations : including a spectroscopic determination of the constant of aberration, the orbits of 13 spectroscopic binary stars, and the radial velocities of 434 stars", Annals of the Cape Observatory, 10: 246, Bibcode:1928AnCap..10....8S.
  8. ^ a b c Montesinos, B.; et al. (September 2016), "Incidence of debris discs around FGK stars in the solar neighbourhood", Astronomy & Astrophysics, 593: 31, arXiv:1605.05837, Bibcode:2016A&A...593A..51M, doi:10.1051/0004-6361/201628329, A51.
  9. ^ a b c David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146.
  10. ^ a b "1 Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-09.
  11. ^ Hauck, B. (1979), "Correlation of spectroscopic and photometric data", International Astronomical Union, Colloquium on Spectral Classification of the Future, Vatican City, July 11–15, 1978. Ricerche Astronomiche (IAU Colloquium 47), 9: 161–178, Bibcode:1979RA......9..161H.
  12. ^ Houk, Nancy (1979), "Michigan catalogue of two-dimensional spectral types for the HD stars", Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume_3. Declinations -40_ƒ0 to -26_ƒ0, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, 3, Bibcode:1982mcts.book.....H.