Omega Canis Majoris

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ω Canis Majoris
Location of ω Canis Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Canis Major[1]
Right ascension 07h 14m 48.654s[2]
Declination −26° 46′ 21.60″[2]
Apparent magnitude (V) 3.60 to 4.18[3]
Characteristics
Spectral type B2.5Ve[4]
U−B color index −0.73[5]
B−V color index −0.14[5]
Variable type γ Cas[3]
Astrometry
Radial velocity (Rv)23.2±2.4[6] km/s
Proper motion (μ) RA: −11.617 mas/yr[2]
Dec.: +8.109 mas/yr[2]
Parallax (π)3.5610±0.1524 mas[2]
Distance920 ± 40 ly
(280 ± 10 pc)
Absolute magnitude (MV)−3.21[1]
Details
Mass10.1±0.7[7] M☉
Radius6.2[8] R☉
Luminosity13,081[9] L☉
Surface gravity (log g)3.5[10] cgs
Temperature21,878[10] K
Rotational velocity (v sin i)80[11] km/s
Age22.5±2.6[7] Myr
Other designations
ω CMa, 28 Canis Majoris, CD−26°4073, GC 9625, HD 56139, HIP 35037, HR 2749, SAO 173282[12]
Database references
SIMBADdata

Omega Canis Majoris is a solitary,[13] blue-white-hued star in the equatorial constellation of Canis Major. Its name is a Bayer designation that is Latinized from ω Canis Majoris, and abbreviated Omega CMa or ω CMa. This star is visible to the naked eye with an apparent visual magnitude of about 4. Based upon an annual parallax shift of 3.56 mas as seen from Earth,[2] this system is located roughly 920 light-years (280 pc) away from the Sun. It is drifting further away with a line of sight velocity of 23 km/s.[6]

Properties

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A visual band light curve for Omega Canis Majoris, adapted from Štefl et al. (2003)[14]

This star has a stellar classification of B2.5Ve, indicating it is a main sequence Be star, although it has also been classified as a subgiant.[15] One of the most observed Be stars of the Southern Hemisphere,[16] Omega Canis Majoris is classified as a Gamma Cassiopeiae-type variable star.[3] Both the luminosity and the radial velocity vary with a primary cyclical period of 1.372 days.[17] The variation in brightness, ranging from magnitude +3.60 to +4.18,[3] shows changes over time, which suggests there are two overlapping periods of 1.37 and 1.49 days. The star also undergoes transient periodicities following outbursts.[18][11]

This is a massive star with ten[7] times the mass of the Sun and 6.2[8] times the Sun's radius. At an estimated age of 22.5 million years,[7] it is radiating 13,081[9] times the Sun's luminosity from its photosphere at an effective temperature of 21,878 K.[10] The star is being viewed nearly pole on, so the measured projected rotational velocity of 80 km/s is only a fraction of the true equatorial velocity, estimated as 350 km/s. It is surrounded by a symmetric circumstellar decretion disk of material that is being heated by the star, which in turn is inserting emission lines into the combined spectrum.[11]

References

[edit | edit source]
  1. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). XHIP record for this object at VizieR.
  2. ^ a b c d e Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gaia DR3 record for this source at VizieR.
  3. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  4. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  5. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  6. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  7. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  8. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  9. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  10. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  11. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  12. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  13. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  14. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  15. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  16. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  17. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  18. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
[edit | edit source]
  • Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
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