The WIRED Survey III: An Infrared Excess around the Eclipsing Post-Common Envelope Binary SDSS J030308.35+005443.7

TL;DR

This paper reports the discovery of a significant infrared excess around the eclipsing post-common envelope binary SDSS J030308.35+005443.7, indicating a circumbinary dust disk possibly formed from disrupted rocky bodies or wind condensation.

Contribution

First detection of infrared excess around a non-interacting white dwarf+M dwarf binary, suggesting a circumbinary dust disk with potential planetary system implications.

Findings

Infrared excess detected with WISE in the system.

Presence of a circumbinary dust disk extending from 1.96 Rsun to <0.8 AU.

Variability in K-band correlated with visible ellipsoidal variations.

Abstract

We present the discovery with WISE of a significant infrared excess associated with the eclipsing post-common envelope binary SDSSJ 030308.35+005443.7, the first excess discovered around a non-interacting white dwarf+main sequence M dwarf binary. The spectral energy distribution of the white dwarf+M dwarf companion shows significant excess longwards of 3-microns. A T_eff of 8940K for the white dwarf is consistent with a cooling age >2 Gyr, implying that the excess may be due to a recently formed circumbinary dust disk of material that extends from the tidal truncation radius of the binary at 1.96 Rsun out to <0.8 AU, with a total mass of ~10^20 g. We also construct WISE and follow-up ground-based near-infrared light curves of the system, and find variability in the K-band that appears to be in phase with ellipsoidal variations observed in the visible. The presence of dust might be due to a) material being generated by the destruction of small rocky bodies that are being perturbed by an unseen planetary system or b) dust condensing from the companion's wind. The high inclination of this system, and the presence of dust, make it an attractive target for M dwarf transit surveys and long term photometric monitoring.