Issue |
Astron. Astrophys. Suppl. Ser.
Volume 119, Number 1, October I 1996
|
|
---|---|---|
Page(s) | 37 - 53 | |
DOI | https://doi.org/10.1051/aas:1996226 | |
Published online | 15 October 1996 |
Multi-colour photometric and spectroscopic monitoring of the WN5 star EZ Canis Majoris *
1
Leiden Observatory, Postbus 9513, NL-2300 RA Leiden, The Netherlands
2
Space Research Organisation Netherlands, Sorbonnelaan 2, NL-3584 CA Utrecht, The Netherlands
3
Nordic Optical Telescope, Apartado 474, E-38700 Sta. Cruz de La Palma, Canarias, Spain
4
Kapteyn Laboratory, Postbus 800, 9700 AV Groningen, The Netherlands
Send offprint request to: A.M. van Genderen
Received:
6
December
1995
Accepted:
21
February
1996
We present and analyse photometric and spectroscopic observations of the
WN5 star EZ Canis Majoris obtained over a period of 7 years. We discuss
the changing light curve, the shift in phase of the maxima and point to
flare type variability seen in one night. Small amplitude variations are
reported in another night. We have investigated the change of the average
visual magnitude over a time span of 18 years and found a tentative
cyclic variation with a time scale of 2425d (6.6 yr) with a range of
. This, of course, should be verified. If true, a precession
phenomenon may offer an explanation. The
trend of the maximum light amplitude of the
cycle is also
investigated and it shows a saw-tooth character with a timescale of
. A possible relation with the magnetic activity of the star is
discussed. We conclude that the line emission variability can be caused
by both a single star model with an ever-changing wind and a binary (WN+NS)
model.
Key words: stars: Wolf-Rayet / stars: individual: WR 6 = HD 50896 = EZ CMa / stars: variable / binaries: close
© European Southern Observatory (ESO), 1996