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

We present the discovery of only the third brown dwarf known to eclipse a non-accreting white dwarf. Gaia parallax information and multicolour photometry confirm that the white dwarf is cool (9950 +/- 150 K) and has a low mass (0.45 +/- 0.05 M-circle dot), and spectra and light curves suggest the brown dwarf has a mass of 0.067 +/- 0.006 M-circle dot (70M(Jup)) and a spectral type of L5 +/- 1. The kinematics of the system show that the binary is likely to be a member of the thick disc and therefore at least 5-Gyr old. The high-cadence light curves show that the brown dwarf is inflated, making it the first brown dwarf in an eclipsing white dwarf-brown dwarf binary to be so.