The magnetic system SMSS J1606-1000 as a period bouncer

TL;DR

This paper reports the discovery of a rare binary system consisting of a magnetic white dwarf and a brown dwarf, with an orbital period of 92 minutes, likely in a detached or low-accretion state, and is the nearest such known system.

Contribution

The discovery of the nearest magnetic white dwarf plus brown dwarf binary system with detailed orbital and magnetic properties.

Findings

Orbital period of 92 minutes consistent with photometric data.

System likely in a detached or low-accretion state.

Magnetic white dwarf has a field of about 30 MG.

Abstract

We report the discovery of a rare close binary system, SMSS J160639.78-100010.7, comprised of a magnetic white dwarf with a field of about 30 MG and a brown dwarf. We measured an orbital period of 92 min which is consistent with the photometric period. Minimum and maximum light occur at the orbital quadratures Phi=0.25 and 0.75, respectively, and cannot be caused by reflection on the brown dwarf, but, instead, by a spot on the synchronously rotating magnetic white dwarf. The brown dwarf does not fill its Roche lobe and the system may be in a low-accretion state or, more likely, in a detached state following episodes of mass transfer. SMSS J160639.78-100010.7 is the nearest known magnetic white dwarf plus brown dwarf system.