Beta Columbae

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β Columbae
Diagram showing star positions and boundaries of the Columba constellation and its surroundings
Cercle rouge 100%.svg

Location of β Columbae (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Columba
Right ascension 05h 50m 57.5929s[1]
Declination −35° 46′ 05.9152″[1]
Apparent magnitude (V) 3.105[2]
Spectral type K1 IIICN+1[3]
U−B color index +1.189[2]
B−V color index +1.162[2]
R−I color index +0.58[4]
Radial velocity (Rv) +88.9[5] km/s
Proper motion (μ) RA: +54.77[1] mas/yr
Dec.: 404.20[1] mas/yr
Parallax (π) 37.41 ± 0.12[1] mas
Distance 87.2 ± 0.3 ly
(26.73 ± 0.09 pc)
Mass 1.10 ± 0.20[6] M
Radius 11.5[7] R
Luminosity (bolometric) 56[8] L
Surface gravity (log g) 2.62[3] cgs
Temperature 4,545[3] K
Metallicity [Fe/H] 0.11[3] dex
Age 2[9] Gyr
Other designations
β Col, Beta Columbae, Beta Col, CD−35 2546, CPD−35 752, FK5 223, GC 7364, HD 39425, HIP 27628, HR 2040, LTT 2392, NLTT 15724, PPM 281952, SAO 196240.[10]
Database references

Beta Columbae (β Columbae, β Col) is the second brightest star in the southern constellation of Columba.[9] It has the traditional name Wezn (or Wazn), from the Arabic وزن "weight".[4][9] It has an apparent visual magnitude of 3.1,[2] which is bright enough to be viewed with the naked eye even from an urban location. Parallax measurements place it at a distance of about 87.2 light-years (26.7 parsecs) from Earth.[1]

In Chinese, (), meaning Son, refers to an asterism consisting of β Columbae and λ Columbae.[11] Consequently, β Columbae itself is known as 子二 (Zǐ èr, English: the Second Star of Son.)[12]


The spectrum of Beta Columbae matches a stellar classification of K1 IIICN+1,[10] where the 'III' luminosity class indicates this is a giant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence of stars like the Sun. The notation 'CN+1' indicates a higher than normal level of cyanogen (CN) absorption in the atmosphere of the star.[13] The interferometry-measured angular diameter of this star, after correcting for limb darkening, is 3.99 ± 0.05 mas,[14] which, at its estimated distance, equates to a physical radius of about 11.5 times the radius of the Sun.[7] Despite having expanded to this radius, Beta Columbae only has about a 10% greater mass than the Sun.[6] The outer envelope of this star is radiating energy at an effective temperature of 4,545 K,[3] resulting an orange hue that is typical of a cool, K-type star.[15]

Beta Columbae has a high proper motion across the celestial sphere[16] and is moving at an unusually large speed of 100 km s−1 relative to the Sun.[9] About 107,200 years ago, it made a close approach to the Beta Pictoris system. The estimated separation of the two stars at this time was around 1.9 ly (0.58 pc) and Beta Columbae may have perturbed outlying planetesimals within the debris disk surrounding Beta Pictoris.[16]


  1. ^ a b c d e f 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 et al. (1966), A System of photometric standards 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G 
  3. ^ a b c d e Gray, R. O. et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637 
  4. ^ a b HR 2040, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 5, 2008.
  5. ^ Wielen, R. et al. (1999), Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions 35, Veröffentlichungen des Astronomisches Rechen-Institut Heidelberg, Bibcode:1999VeARI..35....1W 
  6. ^ a b Stello, D. et al. (2008), "Oscillating K Giants with the WIRE Satellite: Determination of Their Asteroseismic Masses", The Astrophysical Journal Letters 674 (1): L53–L56, arXiv:0801.2155, Bibcode:2008ApJ...674L..53S, doi:10.1086/528936 
  7. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1 . The radius (R*) is given by:
    \begin{align} 2\cdot R_*
 & = \frac{(10^{-3}\cdot (26.73\cdot 3.99)\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
 & \approx 22.9\cdot R_{\bigodot}
  8. ^ Mallik, Sushma V. (December 1999), "Lithium abundance and mass", Astronomy and Astrophysics 352: 495–507, Bibcode:1999A&A...352..495M 
  9. ^ a b c d Kaler, James B., "Wazn", Stars (University of Illinois), retrieved 2012-01-04 
  10. ^ a b NLTT 15724 -- High proper-motion Star, database entry, SIMBAD. Accessed on line September 5, 2008.
  11. ^ (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.
  12. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  13. ^ Keenan, Philip C.; Yorka, Sandra B.; Wilson, Olin C. (July 1987), "Recognition and classification of strong-CN giants", Publications of the Astronomical Society of the Pacific 99: 629–636, Bibcode:1987PASP...99..629K, doi:10.1086/132025 
  14. ^ Richichi, A.; Percheron, I.; Khristoforova, M. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039 
  15. ^ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16 
  16. ^ a b Kalas, Paul; Deltorn, Jean-Marc; Larwood, John (May 2001), "Stellar Encounters with the β Pictoris Planetesimal System", The Astrophysical Journal 553 (1): 410–420, arXiv:astro-ph/0101364, Bibcode:2001ApJ...553..410K, doi:10.1086/320632