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Issue A&A
Volume 471, Number 3, September I 2007
Page(s) 951 - 960
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20077110



A&A 471, 951-960 (2007)
DOI: 10.1051/0004-6361:20077110

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

E. Franciosini1, L. Scelsi2, R. Pallavicini1, and M. Audard3, 4

1  INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
    e-mail: francio@astropa.inaf.it
2  Dipartimento di Scienze Fisiche ed Astronomiche, Università di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
3  Integral Science Data Centre, Ch. d'Ecogia 16, 1290 Versoix, Switzerland
4  Geneva Observatory, University of Geneva, Ch. des Maillettes 51, 1290 Sauverny, Switzerland

(Received 16 January 2007 /Accepted 18 June 2007)

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 low-resolution 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 $\log T = 7.0$; any contribution to the X-ray luminosity from cool plasma ($T\sim 2$ 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.


Key words: stars: activity -- stars: coronae -- stars: pre-main sequence -- stars: late-type -- X-rays: stars -- open clusters and associations: individual: Taurus-Auriga



© ESO 2007


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