EZ Canis Majoris

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EZ Canis Majoris
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Canis Major
Right ascension 06h 54m 13.0441s[1]
Declination −23° 55′ 42.011″[1]
Apparent magnitude (V) 6.71 to 6.95[2]
Spectral type WN4[1]
U−B color index −0.89[3]
B−V color index −0.28[3]
R−I color index +0.06[3]
Variable type WR[2]
Proper motion (μ) RA: −3.86[1] mas/yr
Dec.: 4.75[1] mas/yr
Parallax (π) 1.74 ± 0.76[1] mas
Distance 5,900 ly
(1,800[4] pc)
Absolute magnitude (MV) −4.6[4]
Mass 20[5] M
Radius 2.9[4] R
Luminosity (bolometric) 380,000[4] L
Temperature 85,000[4] K
Other designations
EZ CMa, ALS 98, CD−23°4553, CEL 1426, Collinder 121 4, CPD−23°1588, GC 9061, HD 50896, Hen 3-20, HIP 33165, HR 2583, LBN 1052, LMA IC 1613 10, MR 6, PPM 251223, SAO 172546, SH 2-308, TYC 6522-3270-1.[1]
Database references

EZ Canis Majoris (EZ CMa) is a Wolf-Rayet star in the constellation of Canis Major.[1] It has an apparent visual magnitude which varies between 6.71 and 6.95,[2] over a period of 3.766 days.[6] It is the sixth-brightest Wolf-Rayet star.[6]

EZ Canis Majoris shows variations on its spectrum with a period of approximately 3.8 days and it has been proposed it could be a binary star, with a neutron star as companion that would complete an orbit around the Wolf-Rayet with that period, being it the cause of those variations; however it seems more likely that companion does not exist and spectral variations are caused by activity on the star's surface.[6]


  1. ^ a b c d e f g h V* EZ CMa -- Wolf-Rayet Star, database entry, SIMBAD. Accessed on line November 20, 2008.
  2. ^ a b c EZ CMa, database entry, The combined table of GCVS Vols I-III and NL 67-78 with improved coordinates, General Catalogue of Variable Stars, Sternberg Astronomical Institute, Moscow, Russia. Accessed on line November 20, 2008.
  3. ^ a b c HR 2583, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 20, 2008.
  4. ^ a b c d e Spitzer Space Telescope Infrared Spectrograph (IRS) Spectroscopy of the Prototype Wolf-Rayet Star EZ Canis Majoris (HD 50896), Patrick W. Morris, Paul A. Crowther, and Jim R. Houck, Astrophysical Journal Supplement Series 154, #1 (September 2004), pp. 413–417, doi:10.1086/422878, Bibcode2004ApJS..154..413M. Stellar parameters are in Table 1.
  5. ^ §6, Photon loss from the helium Lyα line — the key to the acceleration of Wolf-Rayet winds, W. Schmutz, Astronomy and Astrophysics 321 (May 1997), pp. 268–287, Bibcode1997A&A...321..268S.
  6. ^ a b c The IUE Mega Campaign: Wind Structure and Variability of HD 50896 (WN5) Astrophysical Journal Letters 452 #1, pp. L57 (October 1995) Bibcode1995ApJ...452L..57S