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

TL;DR

This paper reports the first ground-based detection of thermal emission from an extrasolar planet at optical wavelengths, measuring a secondary eclipse of OGLE-TR-56b with implications for its atmospheric properties.

Contribution

It presents the first ground-based optical detection of thermal emission from an exoplanet during secondary eclipse, using combined VLT and Magellan data.

Findings

Detected a flux decrement of 0.0363% during secondary eclipse.

Estimated a planetary brightness temperature of approximately 2718 K.

Indicated a low albedo and minimal heat redistribution in the planet's atmosphere.

Abstract

We report on the detection of the secondary eclipse of the very-hot Jupiter OGLE-TR-56b from combined z-band time series photometry obtained with the VLT and Magellan telescopes. We measure a flux decrement of 0.0363+/-0.0091 percent 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.