Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraints on the disk geometry of the T Tauri star AA Tau from linear
  polarimetry   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~90 deg., i.e., that the disk's major axis is oriented
in the East-West direction.

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The categories of this paper are: nlin
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The categories of this paper are: chem-ph
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The categories of this paper are: eess
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-bio
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The categories of this paper are: hep-th
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The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: cs
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The categories of this paper are: hep-lat
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The categories of this paper are: physics
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The categories of this paper are: stat