Why are accreting T Tauri stars less luminous in X-rays than non-accretors?

Abstract

Accreting T Tauri stars are observed to be less luminous in X-rays than non-accretors, an effect that has been detected in various star forming regions. To explain this we have combined, for the first time, a radiative transfer code with an accretion model that considers magnetic fields extrapolated from surface magnetograms obtained from Zeeman-Doppler imaging. Such fields consist of compact magnetic regions close to the stellar surface, with extended field lines interacting with the disk. We study the propagation of coronal X-rays through the magnetosphere and demonstrate that they are strongly absorbed by the dense gas in accretion columns.

8 pages, 2 figures, to appear in the proceedings of IAU S243: Star-disk Interaction in Young Stars, Grenoble 2007, eds. J. Bouvier and I. Appenzeller