Investigating the gas-to-dust ratio in the protoplanetary disk of HD 142527. (14th October 2019)

• Record Type: Journal Article
• Authors: Soon, Kang-Lou; Momose, Munetake; Muto, Takayuki; Tsukagoshi, Takashi; Kataoka, Akimasa; Hanawa, Tomoyuki; Fukagawa, Misato; Saigo, Kazuya; Shibai, Hiroshi
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 71:Number 6(2019:Dec.)
• Publication Date: 2019-10-14
• Subjects: protoplanetary disks -- stars: individual (HD 142527) -- stars: pre-main sequence -- submillimeter: planetary systems; Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psz112
• Languages: English
• ISSNs: 0004-6264

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, $\Sigma _\mathrm{g}$ 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 ${}^{13}\mbox{CO}\, J = 3$ –2 with a continuum emission. The gas-to-dust ratio, $\mathrm{G/D}$, varies azimuthally with a relation $\mathrm{G/D} \propto \Sigma _\mathrm{d}^{-0.53}$, 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.