# Speeding past planets? Asteroids radiatively propelled by giant branch Yarkovsky effects

## TL;DR

This paper investigates how intense stellar luminosity during the giant branch phase affects asteroid dynamics through Yarkovsky effects, influencing their fate and distribution around white dwarfs.

## Contribution

It models the impact of giant star luminosity on exo-asteroid migration, highlighting the importance of advanced radiative models for understanding asteroid behavior near white dwarfs.

## Key findings

- Asteroids move too rapidly to be captured by planets during giant branch phase.
- Yarkovsky effects can cause orbital inclination flips without semimajor axis change.
- Resonant trapping of small asteroids by planets is generally insignificant.

## Abstract

Understanding the fate of planetary systems through white dwarfs which accrete debris crucially relies on tracing the orbital and physical properties of exo-asteroids during the giant branch phase of stellar evolution. Giant branch luminosities exceed the Sun's by over three orders of magnitude, leading to significantly enhanced Yarkovsky and YORP effects on minor planets. Here, we place bounds on Yarkovsky-induced differential migration between asteroids and planets during giant branch mass loss by modelling one exo-Neptune with inner and outer exo-Kuiper belts. In our bounding models, the asteroids move too quickly past the planet to be diverted from their eventual fate, which can range from: (i) populating the outer regions of systems out to 10^4-10^5 au, (ii) being engulfed within the host star, or (iii) experiencing Yarkovsky-induced orbital inclination flipping without any Yarkovsky-induced semimajor axis drift. In these violent limiting cases, temporary resonant trapping of asteroids with radii of under about 10 km by the planet is insignificant, and capture within the planet's Hill sphere requires fine-tuned dissipation. The wide variety of outcomes presented here demonstrates the need to employ sophisticated structure and radiative exo-asteroid models in future studies. Determining where metal-polluting asteroids reside around a white dwarf depends on understanding extreme Yarkovsky physics.