AAS 204th Meeting, June 2004
Session 8 UV/Optical Universe at Ultra-High Angular Resolution
Topical Realted Poster, Monday, May 31, 2004, 9:20am-6:30pm, Ballroom

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[8.03] The character of the Eta Car ejecta absorption

G. Vieira (SSAI & NASA/GSFC), K. E. Nielsen (CUA & NASA/GSFC), T. R. Gull (NASA/GSFC), F. Bruhweiler, E. M. Verner (CUA & NASA/GSFC), Eta Car HST Treasury Team

Recent high resolution studies of the \eta\,Car spectrum toward the central source has revealed two discrete absorption components with blue shifts corresponding to -146 and -513 km/s, respectively. We realize that the -146 km/s is associable with the Little Homunculus, ejected during the 1890's event. Its temperature and density is consistent with a distance of 1300 AU to the central source. The -146 km/s component showed a decrease ionization across the minimum during the summer of 2003. Noticeable was the sudden appearance of absorption in \textup{Ti}\,\textsc{ii} 30 days after the X-ray drop only to again disappear. Based on equivalent width measurements of \textup{Fe}\,\textsc{ii} lines the temperature decreased. Satellite velocity components at -168 and -122 km/s appeared. Recent observation shows that the ionization balance in the gas is recovering and the velocity component at -168 km/s is observable no longer. \\ \indent The velocity component at -513 km/s is determined to be at approximately 10\,000 AU from the central source in the wall of the Homunculus. Its spectrum shows little variation across the spectroscopic minimum. Between 1300 -- 1600 Å{} the -513 km/s spectrum is filled with nearly 1000 molecular hydrogen lines from the Lyman bands. We present an initial analysis of the molecular spectrum using a line profile fitting routine to determine the column density of H2. This will help us refine our modeling leading to improved cloud parameters, such as temperature, electron density and distance from the star.

The author(s) of this abstract have provided an email address for comments about the abstract: gvieira@hunin.gsfc.nasa.gov

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Bulletin of the American Astronomical Society, 36 #2
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