X-ray impact on the protoplanetary disks around T Tauri stars G. Aresu, I. Kamp, R. Meijerink, P. Woitke, W.-F. Thi and M. Spaans A&A, 526 (2011) A163 Published online: 17 January 2011 DOI: 10.1051/0004-6361/201015449