Theta Canis Majoris

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Theta Canis Majoris
Canis Major constellation map.svg
Red circle.svg
Location of θ Canis Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Canis Major
Right ascension 06h 54m 11.39877s[1]
Declination −12° 02′ 19.0674″[1]
Apparent magnitude (V) 4.08[2]
Spectral type K4 III[2]
U−B color index +1.69[3]
B−V color index +1.43[3]
Radial velocity (Rv) +96.2±0.1[4] km/s
Proper motion (μ) RA: −137.26[1] mas/yr
Dec.: −15.37[1] mas/yr
Parallax (π) 12.51 ± 0.62[1] mas
Distance 260 ± 10 ly
(80 ± 4 pc)
Absolute magnitude (MV) −0.36±0.15[5]
Mass 0.95±0.03 M
Radius 31.91±1.92 R
Luminosity 263 L
Surface gravity (log g) 1.67±0.08 cgs
Temperature 4,145±26 K
Metallicity [Fe/H] −0.52±0.04 dex
Rotational velocity (v sin i) 2.72±0.40 km/s
Age 10.41±1.31 Gyr
Other designations
θ CMa, 14 CMa, BD−11° 1681, FK5 266, GC 9051, HD 50778, HIP 33160, HR 2574, SAO 152071[6]
Database references

Theta Canis Majoris (θ Canis Majoris) is a solitary,[7] orange-hued star near the northern edge[8] of the constellation Canis Major, forming the nose of the "dog".[9] The star is visible to the naked eye with an apparent visual magnitude of 4.08.[2] Based upon an annual parallax shift of 12.51 mas as seen from Earth,[1] it is located about 260 light years from the Sun. The star is moving away from us with a radial velocity of +96.2 km/s.[4]

This is an old, evolved K-type giant star with a stellar classification of K4 III.[2] It is about ten billion years old with 0.95 times the mass of the Sun, but has expanded to 32 times the Sun's radius. The star is radiating 263 times the Sun's luminosity from its photosphere at an effective temperature of 4,145 K.[4]


  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 d Setiawan, J.; et al. (July 2004), "Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch", Astronomy and Astrophysics, 421: 241–254, Bibcode:2004A&A...421..241S, doi:10.1051/0004-6361:20041042-1. 
  3. ^ a b Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J. 
  4. ^ a b c d Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv:1410.6422Freely accessible, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474. 
  5. ^ da Silva, L.; et al. (November 2006), "Basic physical parameters of a selected sample of evolved stars", Astronomy and Astrophysics, 458 (2): 609–623, arXiv:astro-ph/0608160Freely accessible, Bibcode:2006A&A...458..609D, doi:10.1051/0004-6361:20065105. 
  6. ^ "tet CMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-09-08. 
  7. ^ 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. 
  8. ^ Kaler, James N. (March 8, 2013), "Theta and Lambda Canis Majoris", STARS, University of Illinois, retrieved 2017-09-08. 
  9. ^ Crossen, Craig; Rhemann, Gerald (2012), Sky Vistas: Astronomy for Binoculars and Richest-Field Telescopes, Springer Science & Business Media, p. 112, ISBN 3709106265.