On temperature and abundance effects during an X-ray flare on σ Geminorum
Department of Physics, Technion, Haifa 32000, Israel e-mail: email@example.com
2 Department of Physics, Technion, Haifa 32000, Israel e-mail: firstname.lastname@example.org
3 Paul Scherrer Institut, Würenlingen & Villigen, 5232 Villigen PSI, Switzerland e-mail: email@example.com
Accepted: 20 September 2005
We compare quiescent and flare X-ray spectra of the RS CVn binary σ Gem obtained with the Chandra and XMM-Newton grating spectrometers. We find that in addition to an overall 25% flux increase, which can be ascribed to variations in the system's quiescence activity over the 15 months that passed between the observations, there is a hot plasma component of 3 keV that arises with the flare. The hot component is manifested primarily by emission from high charge states of Fe and by a vast continuum. The cooler (kTe keV) plasma remains undisturbed during the flare. We find no significant variations in the relative abundances during the flare except for a slight decrease (<30%) of O and Ne.
Key words: stars: activity / stars: corona / stars: flares / stars: abundances / stars: individual: σ Geminorum / X-rays: stars
© ESO, 2006