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K. Davidson (UMN), T. R. Gull (GSFC), K. Ishibashi, R.M. Humphreys (UMN)
Our December 1997 and March 1998 STIS data provide the first high-quality view of \eta Car itself, i.e., the star and its wind. All existing ground-based and IUE spectroscopy of Eta is badly contaminated by nearby ejecta, and the only previous spatially resolved data had been obtained using HST's FOS and GHRS, with very incomplete wavelength coverage and other serious limitations.
These STIS observations were intentionally made during the major ``spectroscopic event'' predicted by Damineli. Comparisons with earlier FOS and ground-based data, and comparisons between December and March, show that the physical structure of the wind changed during the event\/ -- a non-trivial result which conflicts with some of the models that had been proposed for Eta's spectroscopic events. The Balmer emission lines, helium emission, calcium H and K lines, and ultraviolet Fe~II absorption and emission all indicate lower ionization throughout the wind. The Balmer alpha line profile is of very high quality and shows surprising structure and changes during the event.
The author(s) of this abstract have provided an email address for comments about the abstract: kd@ea.spa.umn.edu