XMM-Newton observation of the classical T Tauri star SU Aurigae and the surrounding field

Abstract

Aims. We investigate the properties of the X-ray emitting plasma of the classical T Tauri star SU Aurigae and of other sources in the field of view. Methods. We use XMM-Newton to obtain a high-resolution RGS spectrum of SU Aur as well as EPIC imaging data and lowresolution spectra of the star and of other X-ray sources in the surrounding field. We reconstruct the emission measure distribution of SU Aur from the RGS spectrum using a line-based method, and we perform multi-temperature fits of the MOS spectra of the strongest sources both for the full observation and for selected time intervals to study their spectral variability. Results. The emission from SU Aur is highly variable, showing three flares during the observation. The MOS spectra indicate a very hot corona, with significant emissivity up to ∼40 MK in quiescence, and temperatures up to 140 MK during flares. The emission measure distribution derived from the RGS spectrum peaks at logT = 7.0; any contribution to the X-ray luminosity from cool plasma (T ∼ 2 MK) cannot exceed 5% of the total emission. Abundances are ∼0.3−0.6 solar with the exception of Mg and Ne that are solar. Spatial analysis of the full EPIC field results in the detection of 104 X-ray sources, 6 of which are associated with the known Taurus-Auriga members in the field of view (including SU Aur). Conclusions. The characteristics of the X-ray emission of SU Aur are very similar to those of young active late-type stars, with a very hot corona and flares, suggesting magnetic activity as the origin of most of the X-ray emission, rather than accretion.