WD1032 + 011, an inflated brown dwarf in an old eclipsing binary with a white dwarf
Hermes, J. J.; Winget, D. E.; Gänsicke, B. T.; Dhillon, V. S.; Marsh, T. R.; Littlefair, S. P.; Parsons, S. G.; Casewell, S. L.; Burleigh, M. R.; Vanderbosch, Z.; Belardi, C.; Debes, J.; Braker, I. P.; Winget, K. I.
United Kingdom, United States, Spain
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.