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D. R. Gies (CHARA, GSU), E. Kambe (National Defense Academy, Japan), T. Josephs (CHARA, GSU)
We present the results from a continuous 5 day run of IUE UV spectroscopic observations in 1996 of the line profile variable star, \epsilon~Per (B0.7~III). We construct cross-correlation functions of the individual spectra with that of a narrow-lined standard to produce a high S/N representation of the blue-to-red moving bump patterns that are observed in optical spectra. We then use time series analysis methods to determine the periodic components of the profile variations (after re-registering the spectra to correct for binary motion). There are at least six periods present (ranging from 8.46~hr to 2.27~hr), and the stronger signals also appear in optical line variations observed in 1986 (although the relative amplitudes have changed significantly). We also present H\alpha and \ion{He}{1} \lambda 6678 profiles from observations made simultaneously with IUE, and we show that the profile variations are essentially identical in the UV and optical ranges. We present arguments that rule out an origin by rotational modulation or by circumstellar gas obscuration, and we suggest instead that the variations are the result of photospheric nonradial pulsations of relatively low degree (l = 3 - 5). There were significant changes (~10% ) in the equivalent widths of the UV wind lines during the IUE run, and we demonstrate that these may be related to episodes of large amplitude, constructive interference between the NRP modes. Thus, inter-mode beating may play an important role in promoting mass loss from this star.
The author(s) of this abstract have provided an email address for comments about the abstract: gies@chara.gsu.edu