On the long-term stability of the Solar System in the presence of weak perturbations from stellar flybys

TL;DR

This study investigates how weak stellar flybys can subtly perturb planetary systems over long timescales, potentially leading to destabilization, with specific implications for the Solar System's stability over billions of years.

Contribution

The paper introduces an analytic model and N-body simulations to quantify the long-term effects of weak stellar flybys on planetary system stability, highlighting their significance.

Findings

Small perturbations can transfer between planets, affecting stability.

Perturbations of about 0.1% in Neptune's orbit can significantly increase destabilization risk.

Long-term integrations show increased likelihood of Solar System destabilization due to stellar flybys.

Abstract

The architecture and evolution of planetary systems are shaped in part by stellar flybys. Within this context, we look at stellar encounters which are too weak to immediately destabilize a planetary system but are nevertheless strong enough to measurably perturb the system's dynamical state. We estimate the strength of such perturbations on secularly evolving systems using a simple analytic model and confirm those estimates with direct N-body simulations. We then run long-term integrations and show that even small perturbations from stellar flybys can influence the stability of planetary systems over their lifetime. We find that small perturbations to the outer planets' orbits are transferred between planets, increasing the likelihood that the inner planetary system will destabilize. Specifically, our results for the Solar System show that relative perturbations to Neptune's semi-major axis of order 0.1% are strong enough to increase the probability of destabilizing the Solar System within 5 Gyrs by one order of magnitude.