Collisional heating and compaction of small bodies: Constraints for their origin and evolution

TL;DR

This study analyzes previous simulations to understand how collisions have heated and compacted small Solar System bodies, revealing a dichotomy in impact processing and implications for their origins and evolution.

Contribution

It provides new insights into the extent of collisional heating and compaction in large porous small bodies, expanding understanding beyond previous smaller-object studies.

Findings

Impact processing is generally greater in larger bodies.

Escaping material experiences more heating than material in the largest remnant.

Differences between asteroids Ryugu and Bennu may relate to their original locations in parent bodies.

Abstract

The current properties of small bodies provide important clues to their origin and history. However, how much small bodies were processed by past collisions and to what extent they retain a record of processes that took place during the formation and early evolution of the Solar System is still poorly understood. Here we study the degree of collisional heating and compaction by analysing the large set of previous simulations of small body break-ups by Jutzi et al. (2019), which used porous targets of 50 - 400 km in diameter and investigated a large range of impact velocities, angles as well as energies. We find that the degree of impact processing is generally larger than found in previous studies which considered smaller objects (e.g. Jutzi et al., 2017; Schwartz et al., 2018). However, there is a clear dichotomy in terms of impact processing: the escaping material always experiences stronger heating than the material bound to the largest remnant. Assuming they originate from the same parent body, some of the observed differences between the recently visited asteroids Ryugu and Bennu may be explained by a different location of the material eventually forming these asteroids in the original parent body. Our results also provide constraints on the initial size of cometary nuclei.