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 Å , which is maximally formed at 130 MK .