Coagulation of Ice-coated particles is limited

Hauyu Baobab Liu^1*

¹Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan

* Presenter:Hauyu Baobab Liu, email:baobabyoo@gmail.com

PDS70 is one of the only two protoplanetary disks that the forming planets have been confirmed by direct imaging observations. I will present the first Atacama Large Millimeter/submillimeter polarization observations on this source. We detected 1%-2.5% linear polarization, with polarization position angles aligned with the minor axis of the disk. By performing Markov Chain Monte Carlo (MCMC) fitting using Monte Carlo radiative transfer simulations, we found that the maximum dust grain size in the bulk of the PDS70 disk is around 80 micron, which corresponds to a dust fragmentation velocity of ~1 m/s. This indicates that the coagulation of water-ice-coated dust is, in general, not efficient enough to quickly form centimeter-sized pebbles over few Myrs timescales, except in some specific local environments (e.g., vortices) that are too small to be spatially resolved by observations with ~10 AU resolution.

Keywords: dust growth, planet formation, ALMA, polarimetry