paper

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

arXiv:0704.2958 · doi:10.1111/j.1745-3933.2007.00328.x

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 disc. 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. The reduction in the observed X-ray emission depends on the field geometry, which may explain why accreting T Tauri stars show a larger scatter in their observed X-ray luminosity compared to non-accreting stars.

5 pages, 2 figures (reduced quality). Accepted for publication in MNRAS Letters

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