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Session 34 - New Results on the Nature of Eta Carinae.
Oral session, Wednesday, January 07

[34.02] X-ray Spectral Variability of Eta Carinae

M. F. Corcoran (USRA/LHEA-GSFC), R. Petre, J. H. Swank (LHEA-GSFC), K. Ishibashi, K. Davidson (U. Minn.), S. Drake (USRA/LHEA-GSFC), K. Koyama, Y. Tsuboi (Kyoto University), A. Damineli (JILA), R. Viotti (IAS)

We have obtained spatially resolved X-ray spectra in the 0.5-10 keV band of the peculiar, extremely luminous star \eta Car with the Advanced Satellite for Cosmology and Astrophysics (ASCA) X-ray observatory during Cycle 4 observations in mid-1996, along with 2 target-of-opportunity pointings during an X-ray "flare" event in Jul 1997. The ASCA spectra indicate the presence of a thermal component with a temperature near 0.3 keV, along with a much hotter, highly absorbed component at a temperature near 8 keV. We identify line emission from ions of Si and S, and numerous strong transitions from Fe in a variety of ionization stages (from Fe I to Fe XXVI). The line ratios of the Fe transitions produced by the hot plasma are consistent with thermal equilibrium models. The line strengths suggest that Fe is slightly underabundant, S and Si somewhat overabundant, and N highly enriched. We compare all the available ASCA spectra of \eta Car and show significant variability on timescales of days--months.

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Program listing for Wednesday