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κ Centauri
Location of κ Centauri (circled)
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Centaurus
Right ascension 14h 59m 09.68494s [1]
Declination −42° 06′ 15.1069″
Apparent magnitude (V) +3.14 [2]
Characteristics
Spectral type B2 IV [3]
U−B color index −0.805 [2]
B−V color index −0.204 [2]
Variable type Candidate β Cep [4]
Astrometry
Radial velocity (Rv)+8.0 [5] km/s
Proper motion (μ) RA: −17.62 [1]  mas/ yr
Dec.: −22.51 [1]  mas/ yr
Parallax (π)8.51 ± 0.54  mas [1]
Distance380 ± 20  ly
(118 ± 7  pc)
Absolute magnitude (MV)–2.2 [6]
Details
κ Cen A
Mass7.2 ± 0.5 [3]  M☉
Radius4.4 ± 0.7 [3]  R☉
Luminosity2,500 [3]  L☉
Surface gravity (log g)4.02 ± 0.20 [3]  cgs
Temperature19,800 ± 900 [3]  K
Rotational velocity (v sin i)10 [7] km/s
Age18.2 ± 3.2 [8]  Myr
κ Cen B
Mass5 [9]  M☉
Other designations
CD−41°9342, FK5 553, HD 132200, HIP 73334, HR 5576, SAO 225344. [10]
Database references
SIMBAD data

Kappa Centauri (κ Cen, κ Centauri) is a binary star in the southern constellation of Centaurus. With an apparent visual magnitude of +3.14, [2] it can be viewed with the naked eye on a dark night. Parallax measurements place it at an estimated distance of 380 light-years (120 parsecs) from Earth. [1]

This is a spectroscopic binary system where the presence of an orbiting companion is revealed by shifts in the absorption lines caused by the Doppler effect. The primary component is a huge star, with about seven times the Sun's mass and four times the Sun's radius. [3] It has a stellar classification of B2 IV, [3] indicating that it is in the subgiant stage of its stellar evolution. An effective temperature of 19,800 K [3] in the outer envelope is what gives it the blue-white hue of a B-type star. [11]

The primary is a candidate Beta Cephei variable that shows line-profile variations in its spectrum. However, the nature of the variability remains uncertain because of the binary nature of the system. [4] As of 2007, the secondary component was separated from the primary by 0.128  arcseconds at a position angle of 156°. It has about 68% of the mass of the primary. [9] This system is a proper motion member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun. [6]

In Chinese, 騎官 (Qí Guān), meaning Imperial Guards, refers to an asterism consisting of κ Centauri, γ Lupi, δ Lupi, β Lupi, λ Lupi, ε Lupi, μ Lup, π Lupi, ο Lupi and α Lupi. [12] Consequently, the Chinese name for κ Centauri itself is 騎官三 (Qí Guān sān, English: the Third Star of Imperial Guards.). [13] From this Chinese name, the name Ke Kwan has appeared. [14]

See also

References

  1. ^ a b c d e van Leeuwen, F. (November 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
  2. ^ a b c d Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A Photometric Investigation of the Scorpio-Centaurus Association", Astrophysical Journal Supplement, 15: 459, Bibcode: 1968ApJS...15..459G, doi: 10.1086/190168
  3. ^ a b c d e f g h i Hubrig, S.; et al. (January 2009), "New magnetic field measurements of beta Cephei stars and Slowly Pulsating B stars", Astronomische Nachrichten, 330 (4): 317, arXiv: 0902.1314, Bibcode: 2009AN....330..317H, doi: 10.1002/asna.200811187, S2CID  17497112
  4. ^ a b Schrijvers, C.; Telting, J. H.; De Ridder, J. (2002), "A Spectroscopic Search for Non-Radial Pulsations in Early B-Type Stars", in Aerts, Conny; Bedding, Timothy R.; Christensen-Dalsgaard, Jørgen (eds.), Radial and Nonradial Pulsations as Probes of Stellar Physics, ASP Conference Proceedings, vol. 259, San Francisco: Astronomical Society of the Pacific, p. 204, Bibcode: 2002ASPC..259..204S
  5. ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode: 1967IAUS...30...57E
  6. ^ a b de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1–2): 44–61, Bibcode: 1989A&A...216...44D
  7. ^ Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239 (1). Bibcode: 1970CoAsi.239....1B.
  8. ^ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv: 1007.4883, Bibcode: 2011MNRAS.410..190T, doi: 10.1111/j.1365-2966.2010.17434.x, S2CID  118629873
  9. ^ a b Kouwenhoven, M. B. N.; et al. (October 2007), "The primordial binary population. II. Recovering the binary population for intermediate mass stars in Scorpius OB2", Astronomy and Astrophysics, 474 (1): 77–104, arXiv: 0707.2746, Bibcode: 2007A&A...474...77K, doi: 10.1051/0004-6361:20077719, S2CID  15750945
  10. ^ "kap Cen -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-23
  11. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 18, 2012, retrieved 2012-01-16
  12. ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN  978-986-7332-25-7.
  13. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 25 日
  14. ^ Richard Hinckley Allen: Star Names — Their Lore and Meaning: Centaurus
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