Ground-based secondary eclipse detection of the very-hot Jupiter OGLE-TR-56b

Abstract

We report on the detection of the secondary eclipse of the very-hot Jupiter <ns0:ext-link ext-link-type="aoi">OGLE-TR-56b</ns0:ext-link> from combined z'-band time series photometry obtained with the VLT and Magellan telescopes. We measure a flux decrement of 0.0363 ± 0.0091% from the combined Magellan and VLT datasets, which indicates a blackbody brightness temperature of $2718^{+127}_{-107}$ K, a very low albedo, and a small incident radiation redistribution factor, indicating a lack of strong winds in the planet's atmosphere. The measured secondary depth is consistent with thermal emission, but our precision is not sufficient to distinguish between a black-body emitting planet, or emission as predicted by models with strong optical absorbers such as TiO/VO. This is the first time that thermal emission from an extrasolar planet is detected at optical wavelengths and with ground-based telescopes.