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Oxford University Press (OUP), Publications of Astronomical Society of Japan, 2019

DOI: 10.1093/pasj/psz112

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Investigating the gas-to-dust ratio in the protoplanetary disk of HD 142527

This paper was not found in any repository, but could be made available legally by the author.
This paper was not found in any repository, but could be made available legally by the author.

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Data provided by SHERPA/RoMEO

Abstract

Abstract We present ALMA observations of the 98.5 GHz dust continuum and the ${}^{13}\mbox{CO}J = 1$–0 and $\mbox{C}^{18}\mbox{O}J = 1$–0 line emissions of the protoplanetary disk associated with HD 142527. The 98.5 GHz continuum shows a strong azimuthal-asymmetric distribution similar to that of the previously reported 336 GHz continuum, with a peak emission in dust concentrated region in the north. The disk is optically thin in both the 98.5 GHz dust continuum and the $\mbox{C}^{18}\mbox{O}J = 1$–0 emissions. We derive the distributions of gas and dust surface densities, $Σ _\mathrm{g}$ and $Σ _\mathrm{d}$, and the dust spectral opacity index, $β$, 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 ${}^{13}\mbox{CO}\,J = 3$–2 with a continuum emission. The gas-to-dust ratio, $\mathrm{G/D}$, varies azimuthally with a relation $\mathrm{G/D} ∝ Σ _\mathrm{d}^{-0.53}$, and $β$ is derived to be $≈ 1$ and $≈ 1.7$ 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 $Σ _\mathrm{d}$ is located ahead of the peak $Σ _\mathrm{g}$. 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.

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