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[31.01] X-ray Observations of AGB Stars with XMM-Newton

J. H. Kastner (Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology), N. Soker (Technion-Israel Institute of Technology, Haifa, Israel, and Oranim)

We report the preliminary results of an XMM-Newton observing program to determine the X-ray emission properties of a sample of well-studied AGB stars. Our goal is to set constraints on magnetic (dynamo) activity during mass-losing AGB evolutionary stages, and thereby test models wherein AGB star magnetic fields influence mass loss geometry and shape planetary nebulae. We detected X-ray emission from the Mira system, with a total EPIC count rate of ~.11 s^-1. This emission may be due to accretion or magnetic activity associated with Mira B, a companion of uncertain nature located only 0.6" from the mass-losing AGB star. The X-ray spectrum of the Mira system displays emission from highly ionized Ne, and initial (single-component) spectral fits suggest a characteristic emission region temperature ~0 MK, intervening absorbing column ~\times10²¹ cm^-2, and an intrinsic X-ray luminosity of ~\times10²⁹ ergs s^-1. The (apparently single) star T Cas is undetected in X-rays. At the meeting, we will also report on results from observations of TX Cam, an AGB star for which the presence of relatively strong (5-10 G at ~ R_\star) magnetic fields has been inferred from maser polarization measurements in the radio.

This research is partly supported via NASA/GSFC grant NAG5--13158 (XMM-Newton Guest Observer program) to the Center for Imaging Science at Rochester Institute of Technology.

The author(s) of this abstract have provided an email address for comments about the abstract: jhk@cis.rit.edu

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