K Centauri

K Centauri is a possible binary star in the southern constellation of Centaurus. It has a white hue and is bright enough to be visible to the naked eye, having an apparent visual magnitude of +5.04.

This article is about K Centauri. For k Centauri, see 3 Centauri.
K Centauri
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Centaurus
Right ascension 13h 29m 25.25471s[1]
Declination −51° 09′ 54.5048″[1]
Apparent magnitude (V) +5.04[2]
Characteristics
Spectral type A1V[3]
U−B color index +0.07
B−V color index +0.059±0.003[2]
Astrometry
Radial velocity (Rv)−2.0±4.2[2] km/s
Proper motion (μ) RA: -2.094[1] mas/yr
Dec.: -5.548[1] mas/yr
Parallax (π)7.9861 ± 0.2224[1] mas
Distance410 ± 10 ly
(125 ± 3 pc)
Absolute magnitude (MV)−0.91[2]
Details
Mass3.128[4] M☉
Radius6.635[5] R☉
Luminosity248[5] L☉
Surface gravity (log g)2.982[5] cgs
Temperature9,167[5] K
Rotational velocity (v sin i)220.4±2.4[6] km/s
Other designations
K Cen, CD−50°7812, GC 18220, HD 117150, HIP 65810, HR 5071, SAO 240883[7]
Database references
SIMBADdata

K Centauri is located at a distance of approximately 410 light years from the Sun based on parallax, and it has an absolute magnitude of −0.91.[2] This is an ordinary A-type main-sequence star with a stellar classification of A1V.[3] It is spinning rapidly with a projected rotational velocity of 220 km/s,[6] which is giving it a pronounced equatorial bulge that is 25% larger than the polar radius.[8]

Analysis of Hipparcos and Gaia astrometry suggests that the relatively large margins of error in the calculated parallax may be due to orbital motion caused by an unseen companion. The companion would be an 81 MJ object orbiting at about 2 AU.[4]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  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. Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 2, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
  4. Kervella, Pierre; Arenou, Frédéric; Mignard, François; Thévenin, Frédéric (2019), "Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly", Astronomy and Astrophysics, 623: A72, arXiv:1811.08902, Bibcode:2019A&A...623A..72K, doi:10.1051/0004-6361/201834371, S2CID 119491061.
  5. McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017), "Fundamental parameters and infrared excesses of Tycho-Gaia stars", Monthly Notices of the Royal Astronomical Society, 471 (1): 770, arXiv:1706.02208, Bibcode:2017MNRAS.471..770M, doi:10.1093/mnras/stx1433, S2CID 73594365.
  6. Díaz, C. G.; et al. (July 2011), "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum", Astronomy & Astrophysics, 531: A143, arXiv:1012.4858, Bibcode:2011A&A...531A.143D, doi:10.1051/0004-6361/201016386, S2CID 119286673.
  7. "K Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-02-12.
  8. van Belle, Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.
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