Volume 403, Number 1, May III 2003
|Page(s)||155 - 171|
|Section||Stellar structure and evolution|
|Published online||29 April 2003|
Tomography of a stellar X-ray corona: α Coronae Borealis*
Paul Scherrer Institut, Würenlingen & Villigen, CH-5232 Villigen PSI, Switzerland e-mail: firstname.lastname@example.org; email@example.com
2 Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA e-mail: firstname.lastname@example.org
3 SRON National Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands e-mail: email@example.com
Corresponding author: M. Güdel, firstname.lastname@example.org
Accepted: 12 February 2003
We interpret the X-ray light curve obtained by XMM-Newton during a total X-ray eclipse in the nearby binary star α Coronae Borealis. This system consists of a G5 V main-sequence star orbiting an X-ray dark A0 star. The secondary G star is a young, active solar analog with an age of a few 100 Myr. As the primary A star eclipses active regions on the X-ray bright companion, the light curve drops in consecutive steps to zero; as individual active regions reappear during egress, the flux rises in similar steps. The ingress and egress light curves are combined to reconstruct the 2D distribution of X-ray brightness on and around the G star. Three different methods are applied, and variations due to statistical noise and uncertainties in the binary system parameters are discussed. Although the solutions are non-unique, all reconstructions reveal a similar distribution of X-ray bright regions and large areas with little flux. We present plausible estimates of (lower limits to) the electron densities in the bright regions, obtaining characteristic values between 109– cm-3.
Key words: stars: activity / stars: coronae / stars: individual: α CrB / X-rays: stars
© ESO, 2003
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