Stellar Wind Variability from IUE Spectra of Epsilon Orionis

Abstract

21 IUE spectra of epsilon Ori (HD 37128), B0 supergiant, were studied to analyze variations in the profiles of the resonance lines of N V, C IV, Si IV and Si III. The largest variations in the profiles of resonance doublets of N V, C IV and Si IV are found in blue wings of the lines at velocities from --1500 to --2000 km/s, reaching in some spectra up to 50% of the continuum level. Profile variations of the singlet resonance line Si III take place at smaller velocities, from - --300 to --1000 km/s. The observed line profile variations can be explained by the presence either of shells or high velocity clumps in the wind. Corresponding narrow absorption components appear in the blue wings at the velocity about --1700 km/s and sometimes also at - --1400 km/s. They are variable both in strength and in radial velocity, their characteristic life-times being from some days to about a week.