Line Brightness Variations in Alpha Orionis - Phase Differences and Radial Velocities

Observations of the red, bright supergiant star a Orionis (Betelgeuse) during the past decade show significant variations in UV line fluxes and line shifts. Dupree et al. (1987) pointed out that the data from 1984-1987 indicates a periodicity of slightly more than one year in the B magnitude, UV continuum, and Mg II emission line fluxes. Our data shows that this conclusion applies to other strong and medium strong chromospheric lines as well. The variations seem to affect also the relative strength of lines within multiplets.