Collisional Growth Within the Solar System's Primordial Planetesimal Disk and the Timing of the Giant Planet Instability

TL;DR

This paper explores how collisional processes in the early Solar System's primordial disk influenced planet formation and the timing of the giant planet instability, using simulations to support a rapid instability scenario.

Contribution

It provides new insights into the conditions necessary for planet formation in the primordial disk and constrains the timing of the Solar System's dynamical instability.

Findings

Earth-mass trans-Neptunian planets could form within 10 Myr with sufficient collisional damping.

A rapid outer Solar System instability is favored to prevent overproduction of outer planets.

Collisional damping plays a crucial role in early planetesimal evolution.

Abstract

The large scale structure of the Solar System has been shaped by a transient dynamical instability that may have been triggered by the interaction of the giants planets with a massive primordial disk of icy debris. In this work, we investigate the conditions under which this primordial disk could have coalesced into planets using analytic and numerical calculations. In particular, we perform numerical simulations of the Solar System's early dynamical evolution that account for the viscous stirring and collisional damping within the disk. We demonstrate that if collisional damping would have been sufficient to maintain a temperate velocity dispersion, Earth mass trans-Neptunian planets could have emerged within a timescale of 10 Myr. Therefore, our results favor a scenario wherein the dynamical instability of the outer Solar System began immediately upon the dissipation of the gaseous nebula to avoid the overproduction of Earth mass planets in the outer Solar System.