Year: 2024
Type: article
Abstract: ABSTRACT Due to their short orbital periods and relatively high-flux ratios, irradiated brown dwarfs in binaries with white dwarfs offer better opportunities to study irradiated atmospheres than hot Jupiters, which have lower planet-to-star flux ratios. WD1032+011 is an eclipsing, tidally locked white dwarf–brown dwarf binary with a 9950 K white dwarf orbited by a 69.7 M$_{\text{Jup}}$ brown dwarf in a 0.09 d orbit. We present time-resolved Hubble Space Telescope Wide Field Camera 3 spectrophotometric data of WD1032+011. We isolate the phase-dependent spectra of WD1032+011B, finding a 210 K difference in brightness temperature between the dayside and nightside. The spectral type of the brown dwarf is identified as L1 peculiar, with atmospheric retrievals and comparison to field brown dwarfs showing evidence for a cloud-free atmosphere. The retrieved temperature of the dayside is 1748$^{+66}_{-67}$ K, with a nightside temperature of 1555$^{+76}_{-62}$ K, showing an irradiation-driven temperature contrast coupled with inefficient heat redistribution from the dayside to the nightside. The brown dwarf radius is inflated, likely due to the constant irradiation from the white dwarf, making it the only known inflated brown dwarf in an eclipsing white dwarf–brown dwarf binary.
Institutions: University of Leicester, University of Arizona, Space Telescope Science Institute, Johns Hopkins University Applied Physics Laboratory, University of Sheffield, Ames Research Center, Bay Area Environmental Research Institute, University of Virginia, Centre National de la Recherche Scientifique, Université Côte d'Azur, University of Oxford, Lagrange Laboratory, Observatoire de la Côte d’Azur, Shanghai Jiao Tong University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,012
OpenAlex ID: W4402664940