Spot the differences: The X-ray spectrum of SU Aur compared to TW Hya
  We present high-resolution Chandra HETGS X-ray spectra of the classical T Tauri star SU Aur. The quiescent X-ray emission is dominated by a 20-40 MK plasma, which contrasts strongly with the cool 3 MK plasma dominating the X-ray emission of the CTTS TW Hya. A large flare occurred during the first half of our 100 ks observation, and we have modelled the emitting plasma both during this flare and during the apparently quiescent periods. During the flare, an extremely high temperature plasma component (at least 60 MK) accounts for the bulk of the emission. There is an indication of the presence of Fe XXVI emission at 1.78 Angstrom, which is maximally formed at 130 MK. 
K. Smith, M. Audard, M. Guedel, S. Skinner, R. Pallavicini