Theta Columbae

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θ Columbae
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]
Spectral type B8 IV[3]
B−V color index −0.11[2]
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
Distance 720 ± 30 ly
(221 ± 8 pc)
Mass 4.13±0.09[5] M
Luminosity 472[6] L
Temperature 9,916[6] K
Rotational velocity (v sin i) 249[3] km/s
Other designations
θ Col, CD−37° 2609, FK5 2468, HD 42167, HIP 29034, HR 2177, SAO 196514.[7]

Theta Columbae is a solitary[8] 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 an annual parallax shift of just 4.52 mas,[1] it lies roughly 720 light years from the Sun. At that distance, the visual magnitude of the star is reduced by an interstellar extinction factor of 0.11.[9] 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]

For ancient Arabian astronomers, this star, along with ζ CMa, λ CMa, γ Col, δ Col, κ Col, λ Col, μ Col and ξ Col, formed Al Ḳurūd (ألقرد - al-qird), the Apes.[10][11] In Chinese, (Sūn), meaning Grandson, refers to an asterism consisting of θ Columbae and κ Columbae.[12] Consequently, θ Columbae itself is known as 孫二 (Sūn èr, English: the Second Star of Grandson.).[13]

This is an evolving B-type subgiant star with a stellar classification of B8 IV,[3] having recently left the main sequence.[5] 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.[5] It radiates 472 times the solar luminosity from its outer atmosphere at an effective temperature of 9,916 K.[6]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c 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. ^ a b c d 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/0205255Freely accessible, Bibcode:2002A&A...393..897R, doi:10.1051/0004-6361:20020943. 
  4. ^ a b c Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics, 575: 13, arXiv:1412.3648Freely accessible, Bibcode:2015A&A...575A..35B, doi:10.1051/0004-6361/201425221, A35. 
  5. ^ a b c Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052Freely accessible, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691. 
  6. ^ a b c 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:1208.2037Freely accessible. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. 
  7. ^ "tet Col -- Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-12-23. 
  8. ^ 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:0806.2878Freely accessible, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x. 
  9. ^ Gontcharov, G. A. (November 2012), "Spatial distribution and kinematics of OB stars", Astronomy Letters, 38 (11): 694−706, arXiv:1606.09028Freely accessible, Bibcode:2012AstL...38..694G, doi:10.1134/S1063773712110035. 
  10. ^ Allen, Richard Hinckley (1963), "Columba Noae, Noah's Dove", Star Names: their Lore and Meaning (Dover ed.). 
  11. ^ Davis Jr., G. A. (October 1944), "The Pronunciations, Derivations, and Meanings of a Selected List of Star Names", Popular Astronomy, 18: 14, Bibcode:1944PA.....52....8D. 
  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 16 日