WD1032 + 011, an inflated brown dwarf in an old eclipsing binary with a white dwarf
S. L. Casewell, Claudia Belardi, S. G. Parsons, S. P. Littlefair, I. P. Braker, J. J. Hermes, John H. Debes, Zachary P. Vanderbosch, M. R. Burleigh, B. T. Gänsicke, V. S. Dhillon, T. R. Marsh, D. E. Winget, K. I. Winget
Abstract
ABSTRACT 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.