Binary star influence on post-main-sequence multi-planet stability

TL;DR

This study investigates how binary star companions influence the stability of multi-planet systems during stellar evolution, identifying critical binary distances that trigger planetary instability and potential white dwarf pollution.

Contribution

It provides the first comprehensive simulation-based analysis of binary influence on multi-planet stability across stellar evolution phases.

Findings

Instability triggered within about seven times the outer planet separation for circular binaries.

Binary companions can induce planetary system instability during giant and white dwarf phases.

Results inform the likelihood of white dwarf pollution from planetary system dynamics.

Abstract

Nearly every star known to host planets will become a white dwarf, and nearly 100 planet-hosts are now known to be accompanied by binary stellar companions. Here, we determine how a binary companion triggers instability in otherwise unconditionally stable single-star two-planet systems during the giant branch and white dwarf phases of the planet host. We perform about 700 full-lifetime (14 Gyr) simulations with A0 and F0 primary stars and secondary K2 companions, and identify the critical binary distance within which instability is triggered at any point during stellar evolution. We estimate this distance to be about seven times the outer planet separation, for circular binaries. Our results help characterize the fates of planetary systems, and in particular which ones might yield architectures that are conducive to generating observable heavy metal pollution in white dwarf atmospheres.