Drake, Stephen A.

Contact Email: Steve.Drake@gsfc.nasa.gov
Institute: USRA & NASA/GSFC
First Coauthor: Laura Brenneman
Institute: USRA & NASA/GSFC
Second Coauthor: Nicholas White
Institute: NASA/GSFC
Research URL:http://lheawww.gsfc.nasa.gov/users/drake/drake.html
Subject Area: Binary Stars: Non-interacting
Waveband: X-rays
Technique: Spectroscopy
Presentation: Poster Display
Title: The Chandra HETG/ACIS spectrum of the RS CVn binary UX Ari
Abstract: We have obtained a 50 kilosecond Chandra HETG/ACIS spectrum of the RS CVn binary UX Ari at an epoch when its corona was relatively quiescent, showing only minor variability, and soft, with no significant plasma above a temperature of 2 keV. We discuss the results of both global spectral analyses, and of detailed analyses of individual line complexes. We make comparisons to the Chandra HETG/ACIS spectrum of the active binary Algol that we have also analyzed using similar techniques, and with the previously published analysis of the ASCA/EUVE spectrum of UX Ari by Guedel et al. Highlights of the preliminary analysis of the UX Ari spectrum include: (1) the pattern of elemental abundances exhibits the `anti-FIP' effect seen in other very active coronae, with the noble gases Neon and Argon having about 1.5 and 0.75 times their solar photospheric abundances, while low-FIP elements have values as low as 0.1 solar (Fe and Ni); (2) the MEKAL and APEC plasma emission codes give slightly different results when used to fit the observed spectrum.; and (3) a discussion of the evidence for opacity and/or electron density effects in the He-like complexes of the abundant elements such as O, Mg, and Si.