Tidal evolution of close-in exoplanets in co-orbital configurations

TL;DR

This study uses numerical simulations to explore how tidal forces influence the long-term orbital configurations of co-orbital exoplanets, revealing potential instability and collisions, especially for equal-mass hot-super-Earth pairs.

Contribution

It provides new insights into the tidal evolution and stability of co-orbital exoplanets in 1/1 resonance through detailed numerical modeling.

Findings

Equal-mass co-orbital planets often become unstable due to tidal effects.

Tidal interactions can lead to collisions between co-orbital planets.

Different planetary types (super-Earths, Saturns) exhibit varied dynamical behaviors.

Abstract

In this paper, we study the behavior of a pair of co-orbital planets, both orbiting a central star on the same plane and undergoing tidal interactions. Our goal is to investigate final orbital configurations of the planets, initially involved in the 1/1 mean-motion resonance (MMR), after long-lasting tidal evolution. The study is done in the form of purely numerical simulations of the exact equations of motions accounting for gravitational and tidal forces. The results obtained show that, at least for equal mass planets, the combined effects of the resonant and tidal interactions provoke the orbital instability of the system, often resulting in collision between the planets. We first discuss the case of two hot-super-Earth planets, whose orbital dynamics can be easily understood in the frame of our semi-analytical model of the 1/1 MMR. Systems consisting of two hot-Saturn planets are also briefly discussed.