A rotating, expanding disk in the Wolf-Rayet star EZ Canis Majoris
- Wisconsin Univ., Madison (USA)
The discovery of linear polarization changes across the extended wings of He II lines, mainly the strong 4-3 transition at 4686 A, in the WN5 star EZ CMa, is reported. When the polarization across the line profiles is plotted in the Stokes parameters plane, it traces loops clockwise from the blue wing through line center to the red, rather than straight lines. Such polarization loops are reminiscent of what is observed in the Balmer lines of Be stars. The continuum polarization in EZ CMa can be understood by an axisymmetric, electron-scattering envelope, with the decrease in polarization in He II being caused by an increase in absorptive opacity in the lines and dilution by unpolarized line emission, while the variations in position angle are due to the Doppler-shifted absorptive opacity and/or scattered line photons. As the sense of rotation in the loops is also independent of phase of this alleged Wolf-Rayet + compact binary, the polarized line profiles are the signature of a rotating, expanding wind geometry around a single star. 22 refs.
- OSTI ID:
- 6105450
- Journal Information:
- Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 365; ISSN ASJOA; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
BALMER LINES
BINARY STARS
DOPPLER EFFECT
ELEMENTS
FLUIDS
GASES
HELIUM
MAIN SEQUENCE STARS
MOTION
NONMETALS
OPACITY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
POLARIMETRY
POLARIZATION
RARE GASES
ROTATION
SPECTRA
STARS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR WINDS
WOLF-RAYET STARS