Dust grain shattering in protoplanetary discs: collisional fragmentation or rotational disruption?

TL;DR

This study models dust grain growth in protoplanetary discs, revealing that rotational disruption can be a significant shattering process alongside collisional fragmentation, especially under low turbulence conditions.

Contribution

Introduces a one-dimensional model including both collisional and rotational shattering, highlighting the importance of rotational disruption in grain evolution.

Findings

Rotational disruption can dominate over fragmentation under certain conditions.

Disruption significance depends on grain tensile strength.

Low turbulence (α ≲ 5×10⁻⁴) favors rotational disruption.

Abstract

In protoplanetary discs, the coagulation of dust grains into large aggregates still remains poorly understood. Grain porosity appears to be a promising solution to allow the grains to survive and form planetesimals. Furthermore, dust shattering has generally been considered to come only from collisional fragmentation; however, a new process was recently introduced, rotational disruption. We wrote a one-dimensional code that models the growth and porosity evolution of grains as they drift to study their final outcome when the two shattering processes are included. When simulating the evolution of grains in a disc model that reproduces observations, we find that rotational disruption is not negligible compared to the fragmentation and radial drift. Disruption becomes dominant when the turbulence parameter $\alpha \lesssim 5\xtenpow{-4}$, if the radial drift is slow enough. We show that the importance of disruption in the growth history of grains strongly depends on their tensile strength.