Pollution of single white dwarfs by accretion of many small asteroids

TL;DR

This paper proposes that metal pollution in white dwarfs results from continuous accretion of gas from multiple small asteroids, enabling insights into the compositions of extrasolar minor planets.

Contribution

It introduces a model linking white dwarf pollution to the tidal destruction of numerous small asteroids, providing a new method to study extrasolar planetary compositions.

Findings

White dwarf pollution can be explained by accretion of asteroid debris.

Observations can reveal bulk compositions of extrasolar minor planets.

Continuous accretion explains the lack of infrared excess in some polluted white dwarfs.

Abstract

Extrapolating from the solar system's asteroid belt, we propose that externally-contaminated white dwarfs without an infrared excess may be experiencing continuous accretion of gas-phase material that ultimately is derived from the tidal destruction of multiple small asteroids. If this scenario is correct, then observations of metal-polluted white dwarfs may lead to determining the bulk elemental compositions of ensembles of extrasolar minor planets.