Thermal emission from WASP-33b, the hottest known planet

Abstract

We report ground-based observations at 0.91μm of the occultation of the hot Jupiter WASP-33b by its A5 host star. We measure the planet to be 0.109 ± 0.030per cent as bright as its host star at 0.91μm. This corresponds to a brightness temperature, TB= 3620+200- 250K, significantly higher than the zero-albedo equilibrium temperature for both isotropic re-radiation (2750 ± 37K) and uniform day-side-only re-radiation (3271 ± 44K), but consistent with the zero-redistribution temperature (3515 ± 47K). This indicates that the heat redistribution from the day side of WASP-33b to the night side is inefficient and further suggests that there is immediate re-radiation, and therefore little or no redistribution, of heat within the day side. We also detected the stellar pulsations of WASP-33, which we model as the sum of four sinusoids, with periods of between 42 and 77min and amplitudes of 0.5-1.5 mmag. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.