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TwitterA&A 493, 579-584 (2009)
DOI: 10.1051/0004-6361:200810886
Revealing the fastest component of the DG Tauri outflow through X-rays
H. M. Günther1, 2, S. P. Matt2, and Z.-Y. Li21 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: moritz.guenther@hs.uni-hamburg.de
2 Department of Astronomy, University of Virginia, PO Box 400325, Charlottesville, VA 22904, USA
Received 1 September 2008 / Accepted 4 November 2008
Abstract
Context. Some T Tauri stars show a peculiar X-ray
spectrum that can be modelled by two components with different
absorbing column densities.
Aims. We seek to explain the soft X-ray
component in DG Tau, the best studied of these sources, with an
outflow model, taking observations at other
wavelengths into consideration.
Methods. We constrain the outflow properties through spectral
fitting and employ simple semi-analytical formulae to describe
properties of a shock wave that heats up the X-ray emitting region.
Results. The X-ray emission is consistent with its arising
from the fastest and innermost component of the
optically detected outflow. Only a small fraction of the
total mass loss is required for this X-ray emitting
component. Our favoured model requires shock velocities between 400 and
500 km s-1. For a density >105 cm-3 all dimensions of the
shock cooling zone are only a few AU, so even in
optical observations this cannot be resolved.
Conclusions. This X-ray emission mechanism in outflows may also operate
in other, less absorbed T Tauri stars, in addition to
corona and accretion spots.
Key words: stars: formation -- stars: winds, outflows -- stars: individual: DG Tau -- stars: mass-loss
© ESO 2009