16754

We propose HST time-resolved spectroscopy of a rare comma eclipsing white dwarf-brown dwarf binary. The brown dwarf in the binary is a mid-L dwarf and is irradiated by its 10 comma 000 K white dwarf companion. The brown dwarf totally eclipses the white dwarf and the white dwarf parameters are well defined comma meaning there is a directly measured radius of the brown dwarf comma which is inflated compared to models of field dwarfs at the same age. As such this is the only inflated comma irradiated cloudy L dwarf where atmospheric characterisation is possible comma leading to insights into the processes occurring in the atmosphere. We will obtain phase resolved spectra between 1.1 and 1.7 microns using WFC3 with the G141 set up in time-series mode. We will combine our spectra with global circulation models and atmospheric models todoublePoint 1) Determine the effective temperature of the brown dwarf comma 2) Study day-night heat redistribution in unprecedented detail 3) Determine if there are significant nightside clouds. HST can uniquely obtain the high-precision comma time-resolved comma near-infrared spectroscopy required by our science goals.