Kappa Centauri

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Kappa Centauri
Diagram showing star positions and boundaries of the Centaurus constellation and its surroundings
Cercle rouge 100%.svg

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[1] mas
Distance 380 ± 20 ly
(118 ± 7 pc)
Absolute magnitude (MV) –2.2[6]
Details
κ Cen A
Mass 7.2 ± 0.5[3] M
Radius 4.4 ± 0.7[3] R
Luminosity 2,500[3] L
Surface gravity (log g) 4.02 ± 0.20[3] cgs
Temperature 19,800 ± 900[3] K
Rotational velocity (v sin i) 10[7] km/s
Age 18.2 ± 3.2[8] Myr
κ Cen B
Mass 5[9] M
Other designations
CD−41°9342,FK5 553, HD 132200, HIP 73334, HR 5576, SAO 225344.[10]

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, κ Centauri itself is known as 騎官三 (Qí Guān sān, English: the Third Star of Imperial Guards.).[13] From this Chinese name, the name Ke Kwan was appeared.[14]

See also[edit]

References[edit]

  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 
  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 
  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, Jørgen; Christensen-Dalsgaard, Radial and Nonradial Pulsations as Probes of Stellar Physics, ASP Conference Proceedings 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, 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, P. T.; de Zeeuw; 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 
  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 
  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, retrieved 2012-01-16 
  12. ^ (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. ^ (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