Theta Canis Majoris

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]

Theta Canis Majoris
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]
Characteristics
Spectral type K4 III[2]
U−B color index +1.69[3]
B−V color index +1.43[3]
Astrometry
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
Distance260 ± 10 ly
(80 ± 4 pc)
Absolute magnitude (MV)−0.36±0.15[5]
Details[4]
Mass0.95±0.03 M☉
Radius31.91±1.92 R☉
Luminosity263 L☉
Surface gravity (log g)1.67±0.08 cgs
Temperature4,145±26 K
Metallicity [Fe/H]−0.52±0.04 dex
Rotational velocity (v sin i)2.72±0.40 km/s
Age10.41±1.31 Gyr
Other designations
θ CMa, 14 Canis Majoris, BD−11°1681, FK5 266, GC 9051, HD 50778, HIP 33160, HR 2574, SAO 152071[6]
Database references
SIMBADdata

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]

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. 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. 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. Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv:1410.6422, 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/0608160, 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:0806.2878, 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.
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