The Transit Light Curve Project. VIII. Six Occultations of the Exoplanet TrES-3

TL;DR

This study observed six occultations of exoplanet TrES-3 to constrain its flux and albedo, setting upper limits that inform about its atmospheric properties and cloud coverage.

Contribution

First to provide observational upper limits on TrES-3's flux ratio and albedo from multiple occultations, refining understanding of its atmospheric composition.

Findings

No flux decrements detected, establishing upper limits on flux ratio.

Upper limits on geometric albedo suggest absence of highly reflective clouds.

Limits are close to predicted thermal radiation levels.

Abstract

We present photometry of the exoplanet host star TrES-3 spanning six occultations (secondary eclipses) of its giant planet. No flux decrements were detected, leading to 99%-confidence upper limits on the planet-to-star flux ratio of 0.00024, 0.0005, and 0.00086 in the i, z, and R bands respectively. The corresponding upper limits on the planet's geometric albedo are 0.30, 0.62, and 1.07. The upper limit in the i band rules out the presence of highly reflective clouds, and is only a factor of 2-3 above the predicted level of thermal radiation from the planet.