Kappa Velorum

Kappa Velorum (κ Velorum, abbreviated Kappa Vel, κ Vel; proper name Markeb[7] /ˈmɑːrkɛb/) is a binary star system in the southern constellation of Vela. The two components are designated Kappa Velorum A and B.

Kappa Velorum
(Markeb)
Location of κ Vel (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Vela
Right ascension 09h 22m 06.81761s[1]
Declination –55° 00′ 38.4017″[1]
Apparent magnitude (V) 2.48[2]
Characteristics
Spectral type B2 IV[2]
U−B color index –0.78[2]
B−V color index –0.20[2]
Astrometry
Radial velocity (Rv)21.9[3] km/s
Proper motion (μ) RA: –11.40[1] mas/yr
Dec.: +11.52[1] mas/yr
Parallax (π)5.70 ± 0.30 mas[1]
Distance570 ± 30 ly
(175 ± 9 pc)
Absolute magnitude (MV)−3.74[4]
Orbit[5]
Period (P)116.65 days
Eccentricity (e)0.19
Semi-amplitude (K1)
(primary)		46.5 km/s
Other designations
Markeb, HR 3734, HD 81188, SAO 236891, FK5 353, CPD-54°2219, GC 12938, HIP 45941[6]
Database references
SIMBADdata

From parallax measurements, this system is located at a distance of roughly 572 light-years (175 parsecs) from the Sun. The apparent visual magnitude is 2.48,[2] making it readily visible to the naked eye in the southern hemisphere. It forms part of an asterism known as the False Cross along with Delta Velorum, Iota Carinae and Epsilon Carinae, so called because it is sometimes mistaken for the Southern Cross, causing errors in astronavigation.[8]

Nomenclature

κ Velorum (Latinised to Kappa Velorum) is the system's Bayer designation. The designations of the two components as Kappa Velorum A and B derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[9]

The system had a traditional name Markab,[10] from the Arabic مركب, markab meaning "something to ride".[11] It was often spelled Markeb[12] to distinguish it from similarly named stars such as Alpha Pegasi. In 2016, the IAU organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars. The WGSN approved the name Markeb for Kappa Velorum on 5 September 2017. Markab had previously been approved for Alpha Pegasi on 30 June 2016. Both are now included in the List of IAU-approved Star Names.[7]

In Chinese, 天社 (Tiān Shè), meaning Celestial Earth God's Temple, refers to an asterism consisting of Kappa Velorum, Gamma² Velorum, b Velorum and Delta Velorum.[14] Consequently, Kappa Velorum itself is known as 天社五 (Tiān Shè wǔ), "the Fifth Star of Celestial Earth God's Temple".[15]

Properties

Kappa Velorum is a spectroscopic binary system consisting of a pair of stars that complete an orbit around each other with a period of 116.65 days and an eccentricity of 0.19. Because the individual stars have not been resolved, further details of the orbit have not yet been determined.[5] The combined stellar classification of the pair is B2 IV,[2] which matches the class of a B-type subgiant star that has exhausted the hydrogen at its core and begun to evolve into a giant. It has an estimated size of 6.9 times the Sun's radius.[16]

The system is only a couple of degrees from the south celestial pole of Mars, so it could therefore be considered the southern polar star of that planet. Due to precession of the equinoxes, it will be the closest bright star of note to the south celestial pole of Earth in the period surrounding 9000 AD.

Interstellar medium

Analysis of the spectrum of Kappa Velorum shows absorption lines due to the interstellar medium between Earth and the star. Observation of these features over many years has shown that the lines vary in strength, probably caused by a small dense cloud extending 10²–10³ au moving across the line of sight.[17][18]

References
  1. 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. Denoyelle, J. (March 1977), "The spatial distribution of young stars in Vela (l = 257 to 284 )", Astronomy and Astrophysics Supplement Series, 27: 343–365, Bibcode:1977A&AS...27..343D
  3. 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. Determination of Radial Velocities and Their Applications. Vol. 30. University of Toronto: International Astronomical Union. p. 57. Bibcode:1967IAUS...30...57E.
  4. 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.
  5. Pourbaix, D.; et al. (September 2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424 (2): 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213, S2CID 119387088
  6. "kap Vel -- Spectroscopic binary", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-08
  7. "Naming Stars". IAU.org. Retrieved 16 December 2017.
  8. Moore, Patrick (2010). Patrick Moore's Astronomy: Teach Yourself. Hachette. ISBN 978-1444129779.
  9. Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  10. Burnham, Robert (1978), Burnham's celestial handbook: an observer's guide to the universe beyond the solar system, Dover books explaining science, vol. 3 (2nd ed.), Courier Dover Publications, p. 2037, ISBN 0-486-23673-0, retrieved 2012-01-08
  11. Allen, R. H. (1963). Star Names: Their Lore and Meaning (rep. ed.). New York, NY: Dover Publications Inc. ISBN 0-486-21079-0.
  12. Kunitzsch, P. (February 1986), "John of London and his Unknown Arabic Sources", Journal for the History of Astronomy, 17 (1): 51, Bibcode:1986JHA....17...51K, doi:10.1177/002182868601700104, S2CID 118089032
  13. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  14. (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.
  15. (in Chinese) 香港太空館 – 研究資源 – 亮星中英對照表 Archived 2008-10-25 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
  16. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy and Astrophysics, 367 (2): 5211–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754
  17. Crawford, I. A. (August 2002), "Detection of CaI and CH absorption at the velocity of the variable interstellar component towards κ Velorum", Monthly Notices of the Royal Astronomical Society, 334 (2): L33–L37, Bibcode:2002MNRAS.334L..33C, doi:10.1046/j.1365-8711.2002.05730.x
  18. Smith, K. T.; Fossey, S. J.; Cordiner, M. A.; Sarre, P. J.; Smith, A. M.; Bell, T. A.; Viti, S. (2013). "Small-scale structure in the interstellar medium: Time-varying interstellar absorption towards κ Velorum". Monthly Notices of the Royal Astronomical Society. 429 (2): 939. arXiv:1210.8136. Bibcode:2013MNRAS.429..939S. doi:10.1093/mnras/sts310.
  • "The path of the Southern Celestial Pole": The System of W. B. Yeats's A Vision Diagram of the southern precession circle, showing Markeb as the South Pole Star in 9000 AD.
  • Kaler, James B., "MARKEB (Kappa Velorum)", Stars, University of Illinois, retrieved 2012-01-08
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