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D.P. Huenemoerder, C.R. Canizares, N.S. Schulz, D. Dewey (MIT)
II Peg is one of the most active of the cool, coronal sources known as RS CVn stars. It has been much observed in optical, ultraviolet, and X-rays. Now, high-resolution X-ray spectra have been obtained and the corona can be studied in detail. We observed II Peg for 45 ks last October with the High Energy Transmission Grating Spectrograph on the Chandra X-Ray Observatory. The X-Ray spectrum, with a resolution of up to 1000, contains a wealth of emission lines from many elements, providing diagnostics of coronal temperatures, densities, motions, and variability. The Helium-like triplets of Mg XI, Si XIII, and O VII are particularly useful for densities, while many other lines give information on the temperature structure of the corona. We will present temperature and density diagnostics, a general characterization of the emission measure distribution, coronal abundances, and variability, if any.
This work is supported by NASA (NAS8-38249) and the Chandra X-Ray Center (SAO SV1-61010).