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

WD1032 + 011, an inflated brown dwarf in an old eclipsing binary with a white dwarf Casewell, S.L.; Belardi, C.; Parsons, S.G.; Littlefair, S.P.; Braker, I.P.; Hermes, J.J.; Debes, J.; Vanderbosch, Z.; Burleigh, M.R.; Gänsicke, B.T.; Dhillon, V.S.; Marsh, T.R.; Winget, D.E.; Winget, K.I. 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⊙), and spectra and light curves suggest the brown dwarf has a mass of 0.067 ± 0.006 M⊙ (70MJup) 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.