IUE and balloon spectral observations of mass loss from BET Ori.
Bates, B.; Giaretta, D. L.; McCartney, D. J.; McQuoid, J. A.; Bankhead, R. E. L.
United Kingdom
Abstract
New observations are presented of the ultraviolet spectrum of Beta Ori which were obtained from the International Ultraviolet Explorer and from a high resolution, balloon-borne spectrograph. The blue-shifted, high velocity components (HVC) in the Mg II resonance lines indicate that a small deceleration of the material relative to the star has occurred in the time interval (about 50 day) between the IUE and balloon observations. Assuming that the components correspond to a physical shell, a simple analysis is given which suggests that it is unlikely that the shell can be formed by an instability in a stellar wind of constant mass loss rate. The observational data available are consistent with a model in which the shell is photoionized by Beta Ori. Limits are given on the radius, density and mass of the shell at the time of the IUE observation. The relationship of the present HVC to those previously reported at different velocities is discussed briefly.