Fast methods for tracking grain coagulation and ionization. III. Protostellar collapse with non-ideal MHD

TL;DR

This paper presents numerical simulations of protostellar collapse that incorporate grain coagulation and non-ideal MHD effects, revealing rapid grain growth and its impact on disk dynamics and resistivities.

Contribution

It introduces a self-consistent, low-cost simulation method for evolving grain size distribution with non-ideal MHD effects during star formation.

Findings

Grain sizes grow to over 100 μm within 1000 years in inner disks.

Coagulation efficiency depends on time spent in high-density regions.

Grain growth significantly influences resistivities and disk dynamics.

Abstract

Dust grains influence many aspects of star formation, including planet formation, opacities for radiative transfer, chemistry, and the magnetic field via Ohmic, Hall, and ambipolar diffusion. The size distribution of the dust grains is the primary characteristic influencing all these aspects. Grain size increases by coagulation throughout the star formation process. We describe here numerical simulations of protostellar collapse using methods described in earlier papers of this series. We compute the evolution of the grain size distribution from coagulation and the non-ideal magnetohydrodynamics effects self-consistently and at low numerical cost. We find that the coagulation efficiency is mostly affected by the time spent in high-density regions. Starting from sub-micron radii, grain sizes reach more than 100 {\mu}m in an inner protoplanetary disk that is only 1000 years old. We also show that the growth of grains significantly affects the resistivities, and indirectly the dynamics and angular momentum of the disk.