Collisional growth efficiency of dust aggregates and its independence of the strength of interparticle rolling friction

TL;DR

This study uses numerical simulations to show that the threshold velocity for dust aggregate fragmentation during collisions is nearly unaffected by the strength of interparticle rolling friction, highlighting a key aspect of planet formation processes.

Contribution

It reveals that the collisional growth threshold of dust aggregates is independent of rolling friction strength, clarifying a previously uncertain aspect of dust collision physics.

Findings

Fragmentation threshold is nearly independent of rolling friction strength.

Energy dissipation remains constant despite variations in rolling friction.

Numerical simulations confirm the robustness of collisional outcomes.

Abstract

The pairwise collisional growth of dust aggregates consisting submicron-sized grains is the first step of the planet formation, and understanding the collisional behavior of dust aggregates is therefore essential. It is known that the main energy dissipation mechanisms are the tangential frictions between particles in contact, namely, rolling, sliding, and twisting. However, there is a large uncertainty for the strength of rolling friction, and the dependence of the collisional growth condition on the strength of rolling friction was poorly understood. Here we performed numerical simulations of collisions between two equal-mass porous aggregates with various collision velocities and impact parameters, and we also changed the strength of rolling friction systematically. We found that the threshold of the collision velocity for the fragmentation of dust aggregates is nearly independent of the strength of rolling friction. This is because the total amount of the energy dissipation by the tangential frictions is nearly constant even though the strength of rolling friction is varied.