A Search for Refraction in Kepler Photometry of Gas Giants

TL;DR

This study investigates the potential for detecting atmospheric refraction in Kepler photometry of gas giant exoplanets, aiming to observe subtle brightness changes caused by light bending through their atmospheres.

Contribution

It applies a refraction detection method to Kepler data, testing the Sidis and Sari model, and rules out the model for four gas giant candidates.

Findings

Refraction signals are not detected in the analyzed Kepler data.

The Sidis and Sari model is inconsistent with observations for four candidates.

Abstract

Refraction can lead to a brightening just before ingress and just after egress of a transit, as light passes through the exoplanet's atmosphere and is refracted into our line of sight. Refraction just outside of transit has been seen and modeled in our own solar system during transits of Venus. For short-period planets, the model of Sidis and Sari (2010 ApJ,720,904) implies refraction peaks typically under 100 parts per million and comparable in duration to ingress and egress. Kepler photometry currently provides the best opportunity for detecting refraction. We search for the signature of refraction just outside of transit in Kepler photometry of 45 gas giants and firmly rule out the Sidis and Sari model for four candidates.