Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An Observational Study for Grain Dynamics in the AS 209 Disk with
  Submillimeter Polarization   We present 870 $\mu$m ALMA polarization observation toward the Class
I\hspace{-.1em}I protoplanetary disk around AS 209, which has concentric,
multiple gaps and rings. We successfully detect the polarized emission and find
that the polarization orientations and fractions have distinct characteristics
between the inner and outer regions. In the inner region, the polarization
orientations are parallel to the minor axis of the disk, which is consistent
with the self-scattering model. The mean polarization fraction in the region is
$\sim$0.2\%, which is lower than the expected value when the grains have the
maximum polarization efficiency, which corresponds to $\lambda$/2$\pi$ $\sim$
140 $\mu$m in grain radius. In the outer region, we detect $\sim$1.0\%
polarization and find that the polarization orientations are almost in the
azimuthal directions. Moreover, the polarization orientations have systematic
angular deviations from the azimuthal directions with $\Delta$$\theta$ $\sim$
4\fdg5 $\pm$ 1\fdg6. The pattern is consistent with a model that radially
drifting dust grains are aligned by the gas flow against the dust grains. We
consider possible scenarios of the grain dynamics at the AS 209 ring which can
reproduce the polarization pattern. However, the directions of the observed
angular deviations are opposite to what is predicted under the fact that the
disk rotates clockwise. This poses a question in our understandings of the
alignment processes and/or grain dynamics in protoplanetary disks.

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The categories of this paper are: stat
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
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The categories of this paper are: physics
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The categories of this paper are: math-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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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: comp-gas
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The categories of this paper are: cs