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]
Characteristics
Spectral type F2 V[3]
U−B color index +0.00[4]
B−V color index +0.38[4]
Astrometry
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 mas[1]
Distance63.3 ± 0.2 ly
(19.40 ± 0.07 pc)
Absolute magnitude (MV)+2.81[6]
Orbit[7]
Period (P)9.94480±0.00441 d
Eccentricity (e)0.247±0.105
Periastron epoch (T)2,422,737.382 ± 3.35 JD
Argument of periastron (ω)
(secondary)		137.7±25.4°
Semi-amplitude (K1)
(primary)		6.00±0.75 km/s
Details
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
Rotation2.42±0.22[8]
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
SIMBADdata

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]

References

  1. 1 2 3 4 5 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. S2CID 18759600. Vizier catalog entry
  2. 1 2 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, S2CID 119257644.
  3. 1 2 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: 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
  4. 1 2 Hoffleit, Dorrit; Jaschek, Carlos (1991). "The Bright star catalogue". New Haven. Bibcode:1991bsc..book.....H.
  5. 1 2 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, S2CID 59451347, A61.
  6. 1 2 3 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. 1 2 3 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. 1 2 3 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, S2CID 55251562, A51.
  9. 1 2 3 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, S2CID 33401607.
  10. 1 2 "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.
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