EDP Sciences
Free Access
Volume 446, Number 2, February I 2006
Page(s) 621 - 626
Section Stellar structure and evolution
DOI https://doi.org/10.1051/0004-6361:20054018
Published online 13 January 2006
A&A 446, 621-626 (2006)
DOI: 10.1051/0004-6361:20054018

On temperature and abundance effects during an X-ray flare on $\sigma$ Geminorum

R. Nordon1, E. Behar2 and M. Güdel3

1  Department of Physics, Technion, Haifa 32000, Israel
    e-mail: nordon@physics.technion.ac.il
2  Department of Physics, Technion, Haifa 32000, Israel
    e-mail: behar@physics.technion.ac.il
3  Paul Scherrer Institut, Würenlingen & Villigen, 5232 Villigen PSI, Switzerland
    e-mail: guedel@astro.phys.ethz.ch

(Recived 9 August 2005 / Accepted 20 September 2005 )

We compare quiescent and flare X-ray spectra of the RS CVn binary $\sigma$ 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 $kT_{\rm e} \ga$ 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 ( $kT_{\rm e}$ $\la 2$ 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: $\sigma$ Geminorum -- X-rays: stars

SIMBAD Objects

© ESO 2006

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.