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تسجيل مستخدم جديدThe Emission Spectrum of the Hot Jupiter WASP-79b from HST/WFC3
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The hot Jupiter WASP-79b is a prime target for exoplanet atmospheric characterization both now and in the future. Here we present a thermal emission spectrum of WASP-79b, obtained via Hubble Space Telescope Wide Field Camera 3 G141 observations as part of the PanCET program. Given the temporal coverage of WASP-79bs secondary eclipse, we consider two scenarios: a fixed mid-eclipse time based on the expected occurrence time and a mid-eclipse time as a free parameter. In both scenarios, we can measure thermal emission from WASP-79b from 1.1-1.7 $mu$m at 2.4$sigma$ confidence consistent with a 1900 K brightness temperature for the planet. We combine our observations with Spitzer dayside photometry (3.6 and 4.5 $mu$m) and compare these observations to a grid of atmospheric forward models. Given the precision of our measurements, WASP-79bs infrared emission spectrum is consistent with theoretical spectra assuming equilibrium chemistry, enhanced abundances of H-, VO, or FeH, as well as clouds. The best match equilibrium model suggests WASP-79bs dayside has a solar metallicity and carbon-to-oxygen ratio, alongside a recirculation factor of 0.75. Models including significant H- opacity provide the best match to WASP-79bs emission spectrum near 1.58 $mu$m. However, models featuring high-temperature cloud species - formed via vigorous vertical mixing and low sedimentation efficiencies - with little day-to-night energy transport also match WASP-79bs emission spectrum. Given the broad range of equilibrium chemistry, disequilibrium chemistry, and cloudy atmospheric models consistent with our observations of WASP-79bs dayside emission, further observations will be necessary to constrain WASP-79bs dayside atmospheric properties.
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