WD1032+011, an inflated brown dwarf in an old eclipsing binary with a white dwarf

TL;DR

This paper reports the discovery of a rare eclipsing binary system comprising a white dwarf and an inflated brown dwarf, providing insights into the properties and evolution of such systems in an old stellar population.

Contribution

It presents the third known white dwarf-brown dwarf eclipsing system, with detailed characterization of the brown dwarf's inflation and system's age, using Gaia data and multi-colour photometry.

Findings

Brown dwarf has a mass of 0.067 MSun and spectral type L5.

The system is likely over 5 billion years old.

The brown dwarf is inflated compared to typical brown dwarfs.

Abstract

We present the discovery of only the third brown dwarf known to eclipse a non-accreting white dwarf. Gaia parallax information and multi-colour photometry confirm that the white dwarf is cool (9950$\pm$150K) and has a low mass (0.45$\pm$0.05~MSun), and spectra and lightcurves suggest the brown dwarf has a mass of 0.067 $\pm$0.006 MSun (70 MJup) and a spectral type of L5 $\pm$1. The kinematics of the system show that the binary is likely to be a member of the thick disk and therefore at least 5 Gyr old. The high cadence lightcurves show that the brown dwarf is inflated, making it the first brown dwarf in an eclipsing white dwarf-brown dwarf binary to be so.