Episodic planetesimal disruptions triggered by dissipation of gas disk

TL;DR

This paper demonstrates that the dissipation of gas in protoplanetary disks triggers episodic catastrophic disruptions of planetesimals through secular and mean motion resonances, explaining early Solar System collisional history.

Contribution

It reveals how gas dissipation-induced resonances can cause episodic planetesimal disruptions, a novel mechanism for early Solar System collisional activity.

Findings

Secular resonances of Jupiter and Saturn induce collisions during nebula dissipation.

Collision frequency decreases after gas dissipation, with planetary embryos driving later collisions.

Resonance-driven disruptions are likely common in protoplanetary disks during gas dissipation.

Abstract

Catastrophic disruptions of planetesimals occur in high-velocity collisions. Radioisotope dating of planetesimal disruption events recorded in meteorites confirms frequent catastrophic collisions in the first $\sim$10 Myr of the Solar System, reflecting a violent environment of the time. However, the nebula gas can damp the eccentricity of planetesimals and suppress the frequency of planetesimal collisions. Strong dynamical mechanisms that excited the protoplanetary disk are required. Here we show that the sweeping secular resonances of Jupiter and Saturn induced by the nebular gas dissipation, together with the mean motion resonances of Jupiter, can trigger a large number of catastrophic collisions, which occur episodically when the secular resonances are at $\sim$2-3 au and continue thereafter. After the gas dissipation completes, catastrophic collisions decrease in frequency, with scattering by planetary embryos becoming the major driving force of the collisions. Our results suggest that the violent environment excited by secular and mean motion resonances can be ubiquitous in protoplanetary disks during nebula dissipation.