Planetesimal collisions as a chondrule forming event

TL;DR

This study uses numerical simulations to investigate planetesimal collisions as a mechanism for chondrule formation, finding that such collisions can produce significant amounts of chondrules consistent with observed data, influenced by impact velocity and target composition.

Contribution

It demonstrates that planetesimal-planetesimal collisions can produce chondrules in amounts comparable to protoplanet collisions, highlighting the importance of impact velocity and target composition.

Findings

Planetesimal collisions produce ~1% chondrules, similar to protoplanet collisions.

Higher impact velocities increase chondrule production.

Deeper regions of large bodies can eject chondrule progenitors.

Abstract

Chondritic meteorites contain unique spherical materials named chondrules: sub-mm sized silicate grains once melted in a high temperature condition in the solar nebula. We numerically explore one of chondrule forming processes, planetesimal collisions. Previous studies found that impact jetting via protoplanet-planetesimal collisions make chondrules with an amount of 1 % of impactors' mass, when impact velocity exceeds 2.5 km s$^{-1}$. Based on the mineralogical data of chondrules, undifferentiated planetesimals would be more suitable for chondrule-forming collisions than potentially differentiated protoplanets. We examine planetesimal-planetesimal collisions using a shock physics code and find two things: one is that planetesimal-planetesimal collisions produce the nearly same amount of chondrules as protoplanet-planetesimal collisions ($\sim$ 1 %). The other is that the amount of produced chondrules becomes larger as the impact velocity increases when two planetesimals collide with each other. We also find that progenitors of chondrules can be ejected from deeper regions of large targets (planetesimals or protoplanets) than small impactors (planetesimals). The composition of targets is therefore important to fully account for the mineralogical data of currently sampled chondrules.