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M. Audard (Columbia University), M. Güdel (Paul Scherrer Institut), S.L. Skinner (CASA/Univ. of Colorado), R. Pallavicini (Palermo Observatory), S.A. Drake (NASA/GSFC), R. Mewe (SRON-Utrecht)
We present Chandra and XMM-Newton high-resolution X-ray spectra of the rapidly rotating giant YY Mensae. It belongs to the class of ``FK Com stars'', i.e. single cool giant stars with projected equatorial velocities measured up to 110 km/s. Chandra and XMM-Newton provide excellent high-resolution X-ray spectra to study the properties of this extreme coronal source. The X-ray spectrum is dominated by a strong continuum component with bright emission lines, mostly from H-like transitions and highly ionized Fe lines (up to Fe XXV), indicative of a very high coronal temperature (\approx 3 keV). The Chandra High-Energy Transmission Grating Spectrometer data are ideal to study at very high resolution this hot coronal source. The Reflection Grating Spectrometer onboard XMM-Newton however provides better information on the cool coronal plasma, and on the carbon and nitrogen abundances. Although no obvious flare was detected in the light curves, YY Men's X-ray luminosity varied by a factor of two between the Chandra and XMM-Newton observations (\log LX \approx 32.16 - 32.42). We derive the coronal emission measure distribution, elemental abundances, and density estimates.
We acknowledge support by SAO grant GO2-3016X.
Bulletin of the American Astronomical Society,
© 2003. The American Astronomical Soceity.