Theta Columbae

Theta Columbae, also named Elkurud /ˈɛlkərʌd/,[10] is a solitary[11] star in the southern constellation of Columba. It is faintly visible to the naked eye, having an apparent visual magnitude of 5.02.[2] Based upon parallax measurements taken during the Hipparcos mission, it is roughly 720 light-years (220 parsecs) distant from the Sun.[1] At its present distance, the visual magnitude of the star is reduced by an interstellar extinction factor of 0.11.[8] It is currently moving away from the Sun with a radial velocity of 45.3 km/s.[4] The star made its closest approach about 4.7 million years ago when it underwent perihelion passage at a distance of 10.9 ly (3.33 pc).[4]

θ Columbae
(Elkurud)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Columba
Right ascension 06h 07m 31.63216s[1]
Declination −37° 15′ 10.5114″[1]
Apparent magnitude (V) 5.02[2]
Characteristics
Spectral type B8 IV[3]
B−V color index −0.11[2]
Astrometry
Radial velocity (Rv)+45.3±1.8[4] km/s
Proper motion (μ) RA: +0.12[1] mas/yr
Dec.: +0.41[1] mas/yr
Parallax (π)4.52 ± 0.16[1] mas
Distance720 ± 30 ly
(221 ± 8 pc)
Absolute magnitude (MV)−1.72[5]
Details
Mass4.13±0.09[6] M☉
Luminosity472[7] L☉
Temperature9,916[7] K
Rotational velocity (v sin i)249[3] km/s
Age237[8] Myr
Other designations
Elkurud, θ Col, CD−37°2609, FK5 2468, HD 42167, HIP 29034, HR 2177, SAO 196514[9]
Database references
SIMBADdata

This is an evolving B-type subgiant star with a stellar classification of B8 IV,[3] having recently left the main sequence.[6] It is spinning rapidly with a projected rotational velocity of 249 km/s.[3] The star has an estimated four times the mass of the Sun.[6] It radiates 472 times the solar luminosity from its outer atmosphere at an effective temperature of 9,916 K.[7]

Nomenclature

θ Columbae, Latinised to Theta Columbae, is the star's Bayer designation.

Early Arab poets referred to a number of anonymous stars as الفرود al-furūd, "the solitary ones". Later Arabian astronomers attempted to identify this name with particular stars, principally in the modern constellations Centaurus and Colomba. Allen (1899) noted the accepted etymology but suggested that al-furūd might have been an old transcriber's error for القرود al-qurūd "the apes", which he rendered "Al Ḳurūd",[12] though this suggested has not received scholarly support.[13]

In 2016, the IAU organized a Working Group on Star Names (WGSN)[14] to catalog and standardize proper names for stars. The WGSN approved the name Elkurud for this star on 1 June 2018, and it is now so included in the List of IAU-approved Star Names.[10] (The historical form Furud was chosen for Zeta Canis Majoris.)

In Chinese, 孫 (Sūn), meaning Grandson, refers to an asterism consisting of Theta Columbae and Kappa Columbae.[15] Consequently, Theta Columbae itself is known as 孫二 (Sūn èr, English: the Second Star of Grandson).[16]

References
  1. 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.
  2. Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1999), "UBVRIJKL photometry of the bright stars", Commission Lunar and Planetary Laboratory, 4: 99, Bibcode:1966CoLPL...4...99J.
  3. Royer, F.; et al. (October 2002), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, arXiv:astro-ph/0205255, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943.
  4. Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics, 575: 13, arXiv:1412.3648, Bibcode:2015A&A...575A..35B, doi:10.1051/0004-6361/201425221, A35.
  5. 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.
  6. Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691.
  7. McDonald, I.; et al. (2012). "Fundamental Parameters and Infrared Excesses of Hipparcos Stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–57. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x.
  8. Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694–706, arXiv:1606.09028, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035.
  9. "tet Col -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-23.
  10. Naming Stars, IAU.org, retrieved 18 June 2018.
  11. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
  12. Allen, Richard Hinckley (1963), "Columba Noae, Noah's Dove", Star Names: their Lore and Meaning (Dover ed.).
  13. Kunitzsch, Paul; Smart, Tim (2006), A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd revised ed.), Cambridge, Massachusetts: Sky Pub, ISBN 978-1-931559-44-7.
  14. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  15. (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.
  16. (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 16 日
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