Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Investigating the gas-to-dust ratio in the protoplanetary disk of HD
  142527   We present ALMA observations of the $98.5~\mathrm{GHz}$ dust continuum and
the $\mathrm{^{13}CO}~J = 1 - 0$ and $\mathrm{C^{18}O}~J = 1 - 0$ line
emissions of the protoplanetary disk associated with HD~142527. The
$98.5~\mathrm{GHz}$ continuum shows a strong azimuthal-asymmetric distribution
similar to that of the previously reported $336~\mathrm{GHz}$ continuum, with a
peak emission in dust concentrated region in the north. The disk is optically
thin in both the $98.5~\mathrm{GHz}$ dust continuum and the $\mathrm{C^{18}O}~J
= 1 - 0$ emissions. We derive the distributions of gas and dust surface
densities, $\Sigma_\mathrm{g}$ and $\Sigma_\mathrm{d}$, and the dust spectral
opacity index, $\beta$, in the disk from ALMA Band 3 and Band 7 data. In the
analyses, we assume the local thermodynamic equilibrium and the disk
temperature to be equal to the peak brightness temperature of
$\mathrm{^{13}CO}~J = 3 - 2$ with a continuum emission. The gas-to-dust ratio,
$\mathrm{G/D}$, varies azimuthally with a relation $\mathrm{G/D} \propto
\Sigma_\mathrm{d}^{-0.53}$, and $\beta$ is derived to be $\approx 1$ and
$\approx 1.7$ in the northern and southern regions of the disk, respectively.
These results are consistent with the accumulation of larger dust grains in a
higher pressure region. In addition, our results show that the peak
$\Sigma_\mathrm{d}$ is located ahead of the peak $\Sigma_\mathrm{g}$. If the
latter corresponds to a vortex of high gas pressure, the results indicate that
the dust is trapped ahead of the vortex, as predicted by some theoretical
studies.

10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int