Three-body Mean Motion Resonance Chains as a Delivery Mechanism for White Dwarf Pollution

TL;DR

This study uses numerical simulations to explore how three-body resonance chains can deliver asteroids to white dwarfs, potentially explaining observed pollution, with findings showing specific resonance conditions and asteroid delivery probabilities.

Contribution

It introduces a novel numerical approach to analyze 3-body resonance chains as a mechanism for white dwarf pollution, highlighting the influence of planetary masses and resonance types.

Findings

Asteroids have up to 1.08% chance of reaching the Roche Limit.

Delivery probability correlates with inner planet mass.

Hotter resonances deliver more asteroids to the Roche Limit.

Abstract

In this work, we used numerical integration of the 4-body problem to study 3-body resonance chains (two planets and an asteroid in the innermost orbit) as a possible mechanism for white dwarf pollution. Two 3-body resonance chains were selected for study: the 6:3:2 and the 4:2:1. Asteroids in both a dynamically colder initial orbit in the 6:3:2 resonance and hotter initial orbits in both resonances were studied. An asteroid had up to a 1.08% chance of being delivered to the stellar Roche Limit of the white dwarf. This probability was strongly linearly correlated with the mass of the inner planet but was not correlated with the mass of the outer planet for both colder and hotter orbits. Average dynamical lifetimes ranged from 23 kyr to 1137 kyr for the dynamically colder orbit and from 12.9 kyr to 89.2 kyr and 10.8 kyr to 793.4 kyr for the dynamically hotter orbits in the 6:3:2 and 4:2:1 resonances, respectively. Average dynamical lifetime was exponentially anticorrelated with the outer planet mass and usually with the inner planet mass except in one case. The hotter 4:2:1 resonance delivered 1.1 times more asteroids to the stellar Roche Limit than the hotter 6:3:2 resonance. The hotter 6:3:2 resonance delivered 1.2 times more asteroids to the stellar Roche Limit than the colder 6:3:2 resonance. A typical accretion rate for a white dwarf star of 10^8 grams s^-1 could be explained by the accretion of an equivalent mass of one of our simulated asteroids every 13.8 Myr.