A Circumbinary Debris Disk in a Polluted White Dwarf System

TL;DR

This paper reports the discovery of a circumbinary debris disk around a white dwarf with a substellar companion, showing that rocky planetesimal formation can occur in close binary systems despite dynamic constraints.

Contribution

It provides the first evidence of a circumbinary debris disk around a white dwarf with a close binary, challenging previous assumptions about disk configurations.

Findings

Debris disk is beyond the Roche limit and optically thin.

The system exhibits atmospheric metal pollution and infrared excess.

Rocky planetesimal formation is robust around close binaries.

Abstract

Planetary systems commonly survive the evolution of single stars, as evidenced by terrestrial-like planetesimal debris observed orbiting and polluting the surfaces of white dwarfs. This letter reports the identification of a circumbinary dust disk surrounding a white dwarf with a substellar companion in a 2.27 hr orbit. The system bears the dual hallmarks of atmospheric metal pollution and infrared excess, however the standard (flat and opaque) disk configuration is dynamically precluded by the binary. Instead, the detected reservoir of debris must lie well beyond the Roche limit in an optically thin configuration, where erosion by stellar irradiation is relatively rapid. This finding demonstrates that rocky planetesimal formation is robust around close binaries, even those with low mass ratios.