Theta Canis Majoris

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 11.399s[1]
Declination −12° 02′ 19.061″[1]
Apparent magnitude (V) 4.08[2]
Characteristics
Evolutionary stage Red giant
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: −136.454 mas/yr[1]
Dec.: −14.322 mas/yr[1]
Parallax (π)12.0676 ± 0.62 mas[1]
Distance270 ± 10 ly
(83 ± 4 pc)[1]
Absolute magnitude (MV)−0.36±0.15[5]
Details[4]
Mass0.95±0.03 M☉
Radius33.01±0.75[6] R☉
Luminosity304.9±7[6] L☉
Surface gravity (log g)1.67±0.08 cgs
Temperature4196±43[6] 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[7]
Database references
SIMBADdata

Theta Canis Majoris (θ Canis Majoris) is a solitary,[8] orange-hued star near the northern edge[9] of the constellation Canis Major, forming the nose of the "dog".[10] The star is visible to the naked eye with an apparent visual magnitude of 4.08.[2] Based upon an annual parallax shift of 12.07 mas as seen from Earth,[1] it is located about 270 light years from the Sun. The star is moving away from Earth with a radial velocity of +96.2 km/s.[4]

This is a evolved K-type giant star with a stellar classification of K4 III.[2] Theta Canis Majoris is 5% less massive than the Sun,[4] but has expanded to 33 times the Sun's size.[6] This old star, around ten billion years old,[4] is over two times older than the Solar System.[11] It irradiates 305 times the Sun's luminosity from its expanded photosphere at an effective temperature of 4,200 K.[6] This temperature gives it the cool orange hue of a K-type star.[12]

References

[edit]
  1. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  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): 99, Bibcode:1966CoLPL...4...99J.
  4. ^ a b c d e 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, S2CID 53666931. Theta Canis Majoris' database entry at VizieR.
  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, S2CID 9341088.
  6. ^ a b c d e Baines, Ellyn K.; Clark, James H., III; Schmitt, Henrique R.; Stone, Jordan M.; von Braun, Kaspar (2023-12-01). "33 New Stellar Angular Diameters from the NPOI, and Nearly 180 NPOI Diameters as an Ensemble". The Astronomical Journal. 166 (6): 268. Bibcode:2023AJ....166..268B. doi:10.3847/1538-3881/ad08be. ISSN 0004-6256.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ "tet CMa". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-09-08.{{cite web}}: CS1 maint: postscript (link)
  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:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  9. ^ Kaler, James N. (March 8, 2013), "Theta and Lambda Canis Majoris", STARS, University of Illinois, retrieved 2017-09-08.
  10. ^ Crossen, Craig; Rhemann, Gerald (2012), Sky Vistas: Astronomy for Binoculars and Richest-Field Telescopes, Springer Science & Business Media, p. 112, ISBN 978-3709106266.
  11. ^ "How old is the Solar System? Astronomers calculate its age by studying rocks that fall from space". BBC Sky at Night Magazine. Retrieved 2024-09-26.
  12. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on 2013-12-03, retrieved 2012-01-16
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