Issue |
A&A
Volume 462, Number 3, February II 2007
|
|
---|---|---|
Page(s) | L41 - L44 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20066693 | |
Published online | 18 December 2006 |
Letter to the Editor
Discovery of variable X-ray absorption in the cTTS AA Tauri
Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: jschmitt@hs.uni-hamburg.de
Received:
3
November
2006
Accepted:
6
December
2006
We present XMM-Newton X-ray and UV observations of the classical T Tauri star AA Tau covering almost two rotational periods where 8.5 days. Clear, but uncorrelated variability is found at both wavebands. The variability observed at ~2100 Å follows the previously known optical period. Spectral analysis of the X-ray data results in
significant variability in the X-ray absorption such that the times of maximal X-ray absorption and UV extinction coincide. Placing the coronal emission in regions at low up to moderate magnetic latitudes and attribution of the variable X-ray absorption
to accretion curtains and/or the disk warp provides a consistent physical picture. However, the derived X-ray absorption and optical extinction at times of maximal optical/UV brightness, i.e. outside occultation, are difficult to reconcile, requiring additional absorption in a disk wind or a peculiar dust grain distribution.
Key words: X-rays: stars / stars: pre-main sequence / stars: coronae / stars: activity
© ESO, 2007
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