The Great Escape: How Exoplanets and Smaller Bodies Desert Dying Stars

TL;DR

This paper investigates the dynamical evolution of exoplanets and smaller bodies around dying stars by removing the adiabatic approximation, revealing potential ejection or orbit alteration during stellar mass loss phases.

Contribution

It introduces a full two-body model with isotropic mass loss, providing new insights into planetary fate during stellar evolution beyond previous simplified approaches.

Findings

Oort clouds and wide-separation planets can be ejected during AGB evolution.

Most planetary material from supernova progenitors is ejected, limiting first-generation pulsar planets.

Material ejected may significantly contribute to free-floating planetary populations.

Abstract

Mounting discoveries of extrasolar planets orbiting post-main sequence stars motivate studies aimed at understanding the fate of these planets. In the traditional "adiabatic" approximation, a secondary's eccentricity remains constant during stellar mass loss. Here, we remove this approximation, investigate the full two-body point-mass problem with isotropic mass loss, and illustrate the resulting dynamical evolution. The magnitude and duration of a star's mass loss combined with a secondary's initial orbital characteristics might provoke ejection, modest eccentricity pumping, or even circularisation of the orbit. We conclude that Oort clouds and wide-separation planets may be dynamically ejected from 1-7 Solar-mass parent stars during AGB evolution. The vast majority of planetary material which survives a supernova from a 7-20 Solar-mass progenitor will be dynamically ejected from the system, placing limits on the existence of first-generation pulsar planets. Planets around >20 Solar-mass black hole progenitors may easily survive or readily be ejected depending on the core collapse and superwind models applied. Material ejected during stellar evolution might contribute significantly to the free-floating planetary population.