Issue |
A&A
Volume 409, Number 1, October I 2003
|
|
---|---|---|
Page(s) | 163 - 167 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20030936 | |
Published online | 17 November 2003 |
Constraints on the disk geometry of the T Tauri star AA Tau from linear polarimetry*
1
Laboratoire d'Astrophysique de Grenoble, CNRS/UJF UMR 5571, 414 rue de la Piscine, BP 53, 38041 Grenoble Cedex 9, France e-mail: jbouvier@obs.ujf-grenoble.fr; dougados@obs.ujf-grenoble.fr
2
Astronomical Institute of the Academy of Sciences of Uzbekistan, Astronomicheskaya 33, Tashkent 700052, Uzbekistan e-mail: kn@astrin.uzsci.net; smeln@sai.msu.ru
3
Isaac Newton Institute of Chile, Uzbekistan Branch, Santiago, Chile e-mail: newton@reuna.cl
Corresponding author: F. Ménard, menard@obs.ujf-grenoble.fr
Received:
27
March
2003
Accepted:
18
June
2003
We have simultaneously monitored the photometric and polarimetric
variations of the Classical T Tauri star AA Tau during the fall of
2002. We combine these data with previously published polarimetric
data covering two earlier epochs. The phase coverage is complete,
although not contiguous. AA Tau clearly shows cyclic variations
coupled with the rotation of the system. The star-disk system produces
a repeatable polarisation curve where the polarisation increases with
decreasing brightness. The data fit well with the model put forward
by Bouvier et al. (1999) where AA Tau is viewed almost edge-on and its
disk is actively dumping material onto the central star via
magnetospheric accretion. The inner edge of the disk is deformed by
its interaction with the tilted magnetosphere, producing “eclipses”
as it rotates and occults the photosphere periodically. From the shape
of the polarisation curve in the QU-plane we confirm that the
accretion disk is seen at a large inclination, almost edge-on, and
predict that its position angle is PA , i.e., that the
disk's major axis is oriented in the East–West direction.
Key words: accretion: accretion disks / stars: circumstellar matter / stars: pre-main sequence / polarization / stars: individual: AA Tau
© ESO, 2003
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