A Search for Asteroids, Moons, and Rings Orbiting White Dwarfs

TL;DR

This paper explores the potential of the Kepler mission to detect asteroid, moon, and ring transits around white dwarfs, providing a new method to study these systems and their characteristics.

Contribution

It demonstrates that Kepler can detect transits of asteroids, moons, and rings around white dwarfs, and discusses how future missions could expand this research.

Findings

Kepler can detect asteroid transits around white dwarfs.

Monitoring a small number of white dwarfs can reveal asteroid system characteristics.

Moons and rings increase the likelihood of transit detection.

Abstract

Do white dwarfs host asteroid systems? Although several lines of argument suggest that white dwarfs may be orbited by large populations of asteroids, transits would provide the most direct evidence. We demonstrate that the Kepler mission has the capability to detect transits of white dwarfs by asteroids. Because white-dwarf asteroid systems, if they exist, are likely to contain many asteroids orbiting in a spatially extended distribution, discoveries of asteroid transits can be made by monitoring only a small number of white dwarfs, compatible with Kepler's primary mission, which is to monitor stars with potentially habitable planets. Possible future missions that survey ten times as many stars with similar sensitivity and minute-cadence monitoring can establish the characteristics of asteroid systems around white dwarfs, such as the distribution of asteroid sizes and semimajor axes. Transits by planets would be more dramatic, but the probability that they will occur is lower. Ensembles of planetary moons and/or the presence of rings around planets can also produce transits detectable by Kepler. The presence of moons and rings can significantly increase the probability that Kepler will discover planets orbiting white dwarfs, even while monitoring only a small number of them.