Establishing Dust Rings and Forming Planets Within Them

TL;DR

This study investigates how dust rings in protoplanetary disks form and evolve, highlighting the role of dust size and gas pressure perturbations in planetesimal and planet formation.

Contribution

The paper provides new insights into dust dynamics near gas pressure maxima, emphasizing the importance of dust size in ring longevity and planetesimal formation within these rings.

Findings

Larger dust particles ($ au_s \\geq 0.1$) can form massive clumps leading to pebble accretion.

Small dust particles ($ au_s < 0.1$) tend to escape rings within a few drift times.

Dust rings with smaller grains ($ au_s \\lesssim 0.05$--0.1) are more likely to survive without planetary influence.

Abstract

Radio images of protoplanetary disks demonstrate that dust grains tend to organize themselves into rings. These rings may be a consequence of dust trapping within gas pressure maxima wherein the local high dust-to-gas ratio is expected to trigger the formation of planetesimals and eventually planets. We revisit the behavior of dust near gas pressure perturbations enforced by a planet in two-dimensional, shearing box simulations. While dust grains collect into generally long-lived rings, particles with small Stokes parameter $\tau_s < 0.1$ tend to advect out of the ring within a few drift timescales. Scaled to the properties of ALMA disks, we find that rings composed of larger particles ($\tau_s \geq 0.1$) can nucleate a dust clump massive enough to trigger pebble accretion which proceeds to ingest the entire dust ring well within $\sim$1 Myr. To ensure the survival of the dust rings, we favor a non-planetary origin and typical grain size $\tau_s \lesssim 0.05$--0.1. Planet-driven rings may still be possible but if so we would expect the orbital distance of the dust rings to be larger for older systems.