A Robust Launching Mechanism for Freely-Floating Planets from Host Stars with Close-in Planets

TL;DR

This paper proposes a new mechanism where gravitational interactions between different planetary populations can produce freely floating planets and disturb existing planetary orbits.

Contribution

It introduces a robust formation channel for free-floating planets via secular perturbations and gravitational scattering involving binary stars and distant massive planets.

Findings

Gravitational scattering can liberate planets from their host systems.

The process can perturb close-in planetary orbits significantly.

It may induce collisions between planets and stars.

Abstract

Secular perturbations from binary stars and distant massive planets can drive cold planets onto nearly parabolic orbits with pericenter passages extremely close to their host stars. Meanwhile, short-period super-Earths are frequently observed around nearby stars. Gravitational scattering between these two distinct populations can lead to substantial orbital energy exchange, liberating some intruders from the gravitational confinement of their host systems. This process offers a robust formation channel for a subset of the abundant freely floating planet population. It may also significantly perturb the original orbits of close-in planets, induce collisional trajectories between close-in planets and their host stars, and disrupt the dynamical evolution of cold planets toward close stellar encounters.