Fifty-six high-resolution ultraviolet IUE observations of ξ Per [O7.5 III] are presented. The optically thick C IV and N V resonance doublets yield a terminal velocity of v = 2600 km s-1. The spectra reveal dramatic variability in the Si IV P Cygni profiles down to short time scales (≡1 hr). The morphology of the variations is characterized by broad low-velocity (0.5 - 0.7 v) absorption enhancements and high-velocity (≡0.8 v) discrete narrow absorption components. The data suggest evidence that the broad absorption features may gradually evolve into the high-velocity components. Characteristics of the P Cygni profiles, including emission to absorption ratios and mass loss rates, are derived. The role of ionization conditions and episodic formation of shells in accounting for the variability is discussed.
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Prinja et al. (1987) studied this question.