this proposal is concerned with determining the velocity structure in the winds of wolf-rayet (wr) stars. our goal is to understand the effects of rotation on the winds of wr stars. there is evidence from polarization and other observations that some wr stars have rotationally distorted winds. we have developed models for winds around stars that are rapidly rotating. bjorkman and cassinelli (1993) developed the wind compressed disk model which showed that rotation can cause wind material from higher latitude regions to flow towards the equatorial plane. cassinelli, ignace and bjorkman(1994) developed the wind compressed zone (wcz) model for wr stars, in which it is shown that a wr star with a slowly accelerating wind will develop large equatorial density enhancements even if the rotation rate is only 15 % of critical speed. we found that the velocity law determines the degree to which stellar rotation produces a density enhancement near the equatorial plane, and to verify the model, we require better information regarding the velocity increase versus radius. this is best derived from ir observations because regions farther out in the wind, hence at larger velocities, are sampled with increasing ir wavelengths. observations of the recombination lines of heii formed in this region will provide direct information about the magnitude of the outflow speed at various locations in the wind acceleration region. the iso short wavelength spectrometer (sws) provides high sensitivity and resolution of spectral lines over a sufficiently broad range of wavelengths to derive the much needed data for the wr wind velocity structure.
Instrument
SWS01 , SWS06
Temporal Coverage
1996-05-11T08:44:04Z/1997-01-14T21:15:09Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, CASSINELLI et al., 1999, 'THE VELOCITY STRUCTURE OF WOLF-RAYET WINDS FROM INFRARED LINE AND CONTINUUM OBSERVATIONS', 1.0, European Space Agency, https://doi.org/10.5270/esa-o4nlsi8
