XMM - Newton observation of the eclipsing binary Algol

Abstract

We present an XMM-Newton observation of the eclipsing binary Algol which contains an X-ray dark B8V primary and an X-ray bright K2IV secondary. The observation covered the optical secondary eclipse and captured an X-ray flare that was eclipsed by the B star. The EPIC and RGS spectra of Algol in its quiescent state are described by a two-temperature plasma model. The cool component has a temperature around 6.4×10 K while that of the hot component ranges from 2 to 4.0×10 K. Coronal abundances of C, N, O, Ne, Mg, Si and Fe were obtained for each component for both the quiescent and the flare phases, with generally upper limits for S and Ar, and C, N, and O for the hot component. F-tests show that the abundances need not to be different between the cool and the hot component and between the quiescent and the flare phase with the exception of Fe. Whereas the Fe abundance of the cool component remains constant at ∼0.14, the hot component shows an Fe abundance of ∼0.28, which increases to ∼0.44 during the flare. This increase is expected from the chromospheric evaporation model. The absorbing column density NH of the quiescent emission is 2.5×10 20 cm, while that of the flare-only emission is lower than 1.3×10 cm. Together with previous observations, this NH difference suggests that there exists a belt of cool gas above the corona and the belt runs parallel to the equator of the K star. Subject headings: stars: abundance – star: binaries: eclipsing – stars: flare – stars: individual: Algol Particle Astrophysics Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, P.R. China; lufj@mail.ihep.ac.cn Department of Astronomy, Beijing Normal University, Beijing 100875, P.R. China Max-Planck-Institut für Extraterrestrische Physik, 85741 Garching, Germany

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Cite this paper

@inproceedings{Yang2006XMMN, title={XMM - Newton observation of the eclipsing binary Algol}, author={X . J . Yang and F . J . Lu and Bernd Aschenbach and L . S . Chen and S . M . Jia and Ying-xu Chen}, year={2006} }