Trapping dust particles in the outer regions of protoplanetary disks

TL;DR

This paper investigates how gas density inhomogeneities in protoplanetary disks can trap dust particles, promoting growth and retention of millimeter-sized grains, with simulations and observational predictions for ALMA.

Contribution

It introduces a model with sinusoidal gas density bumps to explain dust trapping, growth, and retention in outer protoplanetary disk regions, supported by observational simulations.

Findings

Pressure inhomogeneities can trap dust particles effectively.

Simulated ALMA images show detectable ring structures.

Conditions for dust retention align with observed disk features.

Abstract

In order to explain grain growth to mm sized particles and their retention in outer regions of protoplanetary disks, as it is observed at sub-mm and mm wavelengths, we investigate if strong inhomogeneities in the gas density profiles can slow down excessive radial drift and can help dust particles to grow. We use coagulation/fragmentation and disk-structure models, to simulate the evolution of dust in a bumpy surface density profile which we mimic with a sinusoidal disturbance. For different values of the amplitude and length scale of the bumps, we investigate the ability of this model to produce and retain large particles on million years time scales. In addition, we introduced a comparison between the pressure inhomogeneities considered in this work and the pressure profiles that come from magnetorotational instability. Using the Common Astronomy Software Applications ALMA simulator, we study if there are observational signatures of these pressure inhomogeneities that can be seen with ALMA. We present the favorable conditions to trap dust particles and the corresponding calculations predicting the spectral slope in the mm-wavelength range, to compare with current observations. Finally we present simulated images using different antenna configurations of ALMA at different frequencies, to show that the ring structures will be detectable at the distances of the Taurus Auriga or Ophiucus star forming regions.