An analysis of CoRoT multicolour photometry of exoplanets

TL;DR

This study analyzes CoRoT multicolour photometry of exoplanet transits, providing homogeneous time series and examining chromatic transit parameters to understand planetary characteristics across different wavelengths.

Contribution

It offers a method for cleaning and fitting multicolour transit data, revealing potential chromatic variations in planet-to-star radius ratios among low-mass exoplanets.

Findings

Chromatic light curves were successfully cleaned from contamination and outliers.

Fitted transit parameters show consistent radius ratios across colours for individual planets.

Ensemble analysis suggests peculiar behavior of radius ratios in low-mass planets.

Abstract

We analysed the chromatic data of the planetary transits observed with CoRoT to supply homogeneous time series in each of the CoRoT colours. In a first step, we cleaned the chromatic light curves from the contamination of nearby stars and removed outliers and trends caused by anything different from the planetary transits. Then, we simultaneously fitted the chromatic transits of each planet, obtaining a common solution for the orbital parameters i, t0 and a/Rs, with a particular care in the fitting for different limb-darkening parameters. The planet-to-star radius ratios in the CoRoT colours are compatible when considering one planet at a time, but the ensemble of low-mass planets seems to show a peculiar behaviour of the radius ratios.