27 Canis Majoris

27 Canis Majoris

Blue band light curves for EW Canis Majoris. The main plot shows the long term variability, and the inset plot shows the short term variability. Adapted from Mennickent et al. (1994) and Balona & Rozowsky (1991).[1][2]
Observation data
Epoch J2000      Equinox J2000
Constellation Canis Major
Right ascension 07h 14m 15.21192s[3]
Declination −26° 21′ 09.0312″[3]
Apparent magnitude (V) +4.65[4] (+4.92 + 5.39)[5]
Characteristics
Spectral type B3 IIIpe[6]
B−V color index −0.17±0.16[7]
Variable type γ Cas + β Cep:[8]
Astrometry
Radial velocity (Rv)16.3±3.6[7] km/s
Proper motion (μ) RA: −6.91[3] mas/yr
Dec.: +3.17[3] mas/yr
Parallax (π)1.88 ± 0.32 mas[3]
Distanceapprox. 1,700 ly
(approx. 530 pc)
Absolute magnitude (MV)−4.13[7]
Orbit[9]
Period (P)118.54±11.14 yr
Semi-major axis (a)0.178±0.012″
Eccentricity (e)0.747±0.094
Inclination (i)80.2±1.0°
Longitude of the node (Ω)131.3±3.0°
Periastron epoch (T)1,971.01±0.74
Argument of periastron (ω)
(secondary)		85.0±3.6°
Details
27 CMa A
Mass12.5±2.5[10] M☉
Luminosity (bolometric)15,610[4] L☉
Surface gravity (log g)3.514[11] cgs
Temperature21,061[11] K
Rotational velocity (v sin i)290[11] km/s
Age0.1±0.1[10] Myr
Other designations
27 CMa, EW Canis Majoris, BD−26°4057, GC 9608, HD 56014, HIP 34981, HR 2745, SAO 173264, CCDM J07143-2621, WDS J07143-2621[12]
Database references
SIMBADdata

27 Canis Majoris is a binary star[5] system in the northern constellation of Canis Major,[12] located approximately 1,700 light years away from the Sun.[3] It has the variable star designation EW Canis Majoris;[8] 27 Canis Majoris is the Flamsteed designation. This system is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of +4.65.[4] It is moving away from the Earth with a heliocentric radial velocity of 16 km/s.[7]

The pair of stars in this system were first resolved by W. S. Finsen in 1953, and the split has been widening since that time.[13] The system has an orbital period of around 119 years with an eccentricity of 0.7 and a semimajor axis of 0.178″.[9] The magnitude 4.92[5] primary, designated component A, is a Be star with a stellar classification of B3 IIIpe.[6] It is spinning rapidly with a projected rotational velocity of 290 km/s, compared to a critical velocity of 389 km/s.[11] The star appears to be a Beta Cephei variable[14] with a pulsation period of 0.0919 days and an amplitude of 0.0080 in magnitude.[15]

The magnitude 5.39[5] secondary, component B, is classified as a Gamma Cassiopeiae type variable star. Due to its variable nature, the brightness of the system varies from magnitude +4.42 to +4.82.[8]

  1. ^ Cite error: The named reference Mennickent was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference Balona was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Hohle2010 was invoked but never defined (see the help page).
  5. ^ a b c d Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Woods1958 was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b c Cite error: The named reference Samus2017 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Hartkopf2006 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Tetzlaff2011 was invoked but never defined (see the help page).
  11. ^ a b c d Cite error: The named reference Frémat2005 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Mason1997 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Balona1994 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference stankov2005 was invoked but never defined (see the help page).