Studying exoplanetary atmospheres using Chromatic Line-Profile Doppler Tomography technique

Abstract

We aim to probe the atmospheric composition of extrasolar planets, specifically hot Jupiters, retrieving their transmission spectra via the novel Chromatic LineProfile Tomography method. This new method relies on measuring the spectral line distortions caused by the planet shading parts of the rotating stellar surface, which are reflected in the Cross Correlation Functions (CCFs). Hence, once the transmission spectra is retrieved, it can reveal narrow and broadband features which can provide information about the composition of the planet’s atmosphere. In this project, we developed a Chromatic Doppler Tomography -based methodology able to fit observational data to extract transmission spectra. We used the publicly available SOAP code to produce the Doppler Tomography models which are used to fit observational data via an MCMC fitting procedure. Also, we tested our methodology with ESPRESSO and HARPS-N data of the well-studied hot Jupiter HD 209458b, which were obtained during several transits of the planet. The transmission spectra of HD 209458b obtained through this technique reproduced previous results published in the bibliography, proving that the Chromatic Line-Profile Doppler Tomography methodology presented in this work can be a useful and novel technique to explore the atmospheres of transiting planets