Chondrule dust rim growth: Influence of restructuring using molecular dynamics simulations

TL;DR

This study uses molecular dynamics simulations to analyze how collision energy affects chondrule dust rim growth, revealing thresholds for sticking, compaction, and disruption, and predicting growth outcomes under different turbulence conditions.

Contribution

It introduces a detailed collision energy threshold framework and machine learning predictions to understand dust rim growth dynamics in protoplanetary disks.

Findings

Low-energy collisions cause minimal rim alteration.

Higher energies lead to rim compaction and reduced porosity.

High-energy impacts result in rim disruption and particle ejection.

Abstract

We investigate the influence of disruptive collisions on chondrule rim growth, emphasizing the role of kinetic energy in determining the outcomes of these interactions. We establish a threshold of approximately 10 cm/s for the "hit-and-stick" collision regime, beyond which significant changes occur in the structure of rimmed chondrules. Our findings highlight that at low collision energies (KE $< 10^{-12}$ J), minimal structural alteration takes place, while higher energies (KE up to $10^{-10}$ J) lead to compaction of the rim, reducing both its thickness and porosity. Collisions with energies exceeding $10^{-8}$ J result in the complete disruption of the rim, with particles being expelled from it. These results are correlated with the turbulence levels within the disk, as kinetic energy scales with the relative velocities of colliding particles. Leveraging machine learning models trained on our collision data, we predict changes in rim characteristics and employ these predictions in a Monte Carlo simulation to explore rim growth dynamics. Our simulations reveal that rim development is sustained in low-turbulence environments ($\alpha \leq 10^{-5}$), while intermediate turbulence levels ($\alpha$ = $10^{-3}$ to $10^{-4}$) lead to erosion, preventing further rim accumulation in high-turbulence contexts.