Omega Canis Majoris

ω Canis Majoris
Location of ω Canis Majoris (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Canis Major
Right ascension 07h 14m 48.65387s[1]
Declination −26° 46′ 21.6097″[1]
Apparent magnitude (V) 3.60 - 4.18[2]
Characteristics
Spectral type B2.5Ve[3]
U−B color index −0.73[4]
B−V color index −0.14[4]
Variable type γ Cas[2]
Astrometry
Proper motion (μ) RA: −11.88[1] mas/yr
Dec.: +6.87[1] mas/yr
Parallax (π)3.58 ± 0.17 mas[1]
Distance910 ± 40 ly
(280 ± 10 pc)
Absolute magnitude (MV)−3.21[5]
Details
Mass10.1±0.7[6] M☉
Radius6.2[7] R☉
Luminosity13,081[8] L☉
Surface gravity (log g)3.5[9] cgs
Temperature21,878[9] K
Rotational velocity (v sin i)80[10] km/s
Age22.5±2.6[6] Myr
Other designations
ω CMa, 28 Canis Majoris, CD−26°4073, GC 9625, HD 56139, HIP 35037, HR 2749, SAO 173282[11]
Database references
SIMBADdata

Omega Canis Majoris, Latinized from ω Canis Majoris, is a solitary,[12] blue-white-hued star in the equatorial constellation of Canis Major. It is visible to the naked eye with an apparent visual magnitude of about 4. Based upon an annual parallax shift of just 3.58 mas as seen from Earth,[1] this system is located roughly 910 light-years from the Sun.

A visual band light curve for Omega Canis Majoris, adapted from Štefl et al. (2003)[13]

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.[14] One of the most observed Be stars of the Southern Hemisphere,[15] Omega Canis Majoris is classified as a Gamma Cassiopeiae-type variable star.[2] Both the luminosity and the radial velocity vary with a primary cyclical period of 1.372 days.[16] The variation in brightness, ranging from magnitude +3.60 to +4.18,[2] 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.[17][10]

This is a massive star with ten[6] times the mass of the Sun and 6.2[7] times the Sun's radius. At an estimated age of 22.5 million years,[6] it is radiating 13,081[8] times the Sun's luminosity from its photosphere at an effective temperature of 21,878 K.[9] 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.[10]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference slettebak1982 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Feinstein1979 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Tetzlaff2011 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Underhill1979 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Hohle2010 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Soubiran2010 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference Stefl2010 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Stefl2003 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Skiff2014 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Ghoreyshi2016 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Harmanec1998 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Stefl2000 was invoked but never defined (see the help page).