AAS 203rd Meeting, January 2004
Session 58 Eta Carinae
Poster, Tuesday, January 6, 2004, 9:20am-6:30pm, Hanover Hall

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[58.08] Changes in the Far UV spectrum of Eta Carinae near the 2003 minimum.

R.C. Iping (CUA &NASA's GSFC), T.R. Gull, G. Sonneborn (NASA's GSFC), D. Massa, G.L. Vieira (SGT Inc. & NASA's GSFC), K. E. Nielsen (CUA)

High resolution 905-1180 Åspectra of \eta Carinae have been obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite at nine epochs between February 2000 and June 2003 . This period of time extends from the broad maximum up to the very beginning of the minimum of the 5.52-year period initially discovered by A. Damineli (1996, ApJ,460, L49). The flux levels were unchanged between February 2000 through February 2003 with minor spectral differences. The X-Ray minimum started on June 29, 2003 (M. Corcoran, IAUT 8160). Three observations were accomplished on June 10, June 17 and June 27 leading up to the minimum. Substantial changes were present in the June 10 and June 17 spectra, but a very significant change occurred by June 27, 2003.

Longward of 1100Å, the overall flux dropped 10 to 30 %. Shortward of 1100Å, there are spectral intervals with NO decrease in flux even down to the shortest wavelengths (920--950 Å). This indicates that dust absorption has a negligible role in the observed spectral changes and that line absorptions play a major role. Throughout the spectrum there are intervals ranging in width of 3-10 Åwith strong increased absorption. Significant absorptions may be associated with the red portion of the following stellar wind lines: C III 977, O VI 1031,1037, P V 1117, while other absorption features are much broader, more extended and not clearly associated with well-known spectral transitions. Given the complexity of the STIS echelle spectra taken in this period of time, many of these absorption features are likely due to multiple absorption lines.

This work has been supported in part by NASA grant NAG5-11137 to Catholic University of America.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.