2023MNRAS.522.4875R

In co-orbital planetary systems, two or more planets share the same orbit around their star. Here we test the dynamical stability of co-orbital rings of planets perturbed by outside forces. We test two setups: (i) 'stationary' rings of planets that, when unperturbed, remain equally spaced along their orbit and (ii) horseshoe constellation systems, in which planets are continually undergoing horseshoe librations with their immediate neighbours. We show that a single rogue planet crossing the planets' orbit more massive than a few lunar masses ($0.01\!-\!0.04 {\rm \, M_\oplus }\!\!$ ) systematically disrupts a co-orbital ring of 6, 9, 18, or 42 Earth-mass planets located at 1 au. Stationary rings are more resistant to perturbations than horseshoe constellations, yet when perturbed they can transform into stable horseshoe constellation systems. Given sufficient time, any co-orbital ring system will be perturbed into either becoming a horseshoe constellation or complete destabilization.