Stability of the Outer Planets in Multiresonant Configurations with a Self-gravitating Planetesimal Disk

TL;DR

This study investigates how a massive planetesimal disk influences the stability of outer planets in multiresonant configurations, revealing rapid instabilities that challenge existing models of Solar System evolution.

Contribution

It provides the first self-consistent simulations showing rapid destabilization of multiresonant outer planets due to planetesimal interactions, questioning the Nice model's explanation for the Late Heavy Bombardment.

Findings

Rapid planetary migration within 40 Myr in most models

Enhanced interactions between planetesimals and ice giants

Results conflict with the late heavy bombardment hypothesis

Abstract

We study the effect of a massive planetesimal disk on the dynamical stability of the outer planets assuming, as has been suggested recently, that these were initially locked in a compact and multiresonant configuration as a result of gas-driven migration in a protoplanetary disk. The gravitational interaction among all bodies in our simulations is included self-consistently using the Mercury6.5 code. Several initial multiresonant configurations and planetesimal disk models are considered. Under such conditions a strong dynamical instability, manifested as a rapid giant planet migration and planetesimal disk dispersal, develops on a timescale of less than 40 Myr in most cases. Dynamical disk heating due to the gravitational interactions among planetesimals leads to more frequent interactions between the planetesimals and the ice giants Uranus and Neptune, in comparison to models in which planetesitmal-planetesimal interactions are neglected. On account of the rapid evolution of the multiresonant configurations obtained with fully self-consistent simulations, our results are inconsistent with the dynamical instability origin of the Late Heavy Bombardment as currently considered by the Nice model for the Solar System.