ALMA studies of gas-dust interaction in protoplanetary disks

Hsi-Wei Yen^1*, Pin-Gao Gu¹, I-Hsuan Kuo^1,2, Tze-En Chang¹

¹Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
²Department of Physics, National Taiwan University, Taiepi, Taiwan

* Presenter:Hsi-Wei Yen, email:hwyen@asiaa.sinica.edu.tw

A protoplanetary disk consists of gas and dust. Growth of dust grains to large aggregates and further to planetesimals in a protoplanetary disk is an important step in the standard core accretion scenario of planet formation. The relative motion between gas and dust results in drag force on dust grains and makes dust grains drift, which could subsequently concentrate dust grains and promote grain growth. In this presentation, I will introduce our studies of interaction between the gas and dust grains in the protoplanetary disks around two young stars HD142527 and MWC758 with ALMA observations. Using the ALMA data, we analyzed the dust distributions and gas kinematics in the protoplanetary disks, and found deviations in the gas motion from the circular Keplerian rotation, which are likely excited by planet-disk interaction. From the deviation from the circular Keplerian rotation, in the MWC758 disk, we measured the eccentricity of the gas rotation for the first time, and found that the dust distribution and gas rotation in the inner disk have the same eccentricity. In the HD14257 disk, we found a local pressure maximum and that there is more dust in the pressure maximum compared to other parts in the disk. These results suggest that the gas and dust at inner radii in the MWC758 disk are well coupled and follow the same motion, while in the HD142527 the dust grains are locally concentrated due to the gas pressure gradient, where grain growth may be promoted. Such comparisons between dust distributions and gas kinematics can put constraints on properties of dust grains and physical conditions in protoplantary disks.

Keywords: Planet formation, Protoplanetary disks, Planet-disk interaction, Dust continuum emission, CO line emission