Unveiling the 3D structure of exoplanets with high- spectral resolution observations. – EXOWINDS

Hot Jupiters are the best targets for atmospheric characterisation. The new generation of telescopes such as the JWST will provide quantitative measurements of their chemical composition, allowing to trace their formation history. However, these planets are intrinsically 3D objects and low spectral resolution telescopes usually observe spatially averaged spectra. The thermal and chemical inhomogeneities then become degenerate with the molecular abundances that we try to measure.
High-spectral-resolution observations from large ground based telescopes can solve this problem by measuring spatially resolved atmospheric properties. Indeed, the Doppler shifts due to the wind and the planet rotation allow one to spectroscopically separate lines that form in different part of the planet. Previous work have shown that local variations of the chemistry and wind speeds can be directly measured by high-spectral resolution spectroscopy. These local measurements are crucial to benchmark our understanding of the atmospheric circulation and thermal structure of exoplanet atmospheres. They can differentiate between competing theories as to which mechanism sets the wind speed in these planets.

The goal of this proposal is to determine the 3D thermal, chemical and dynamic structure of the population of hot Jupiter atmospheres using high-spectral resolution observations. For this we propose to combine a forward modelling approach, using 3D non-grey global circulation models (WP1) and a reverse approach by developing a multi-dimensional atmospheric retrieval framework and apply them to the numerous observational programs it is associated with (WP2). Finally, the technical and scientifical knowledge obtained in the proposal will be used to inform the future E-ELT observations of hot exoplanet atmospheres (WP3).

The proposal is supported by more than 300h of telescope times on the biggest observatories (Gemini/MAROON-X and Gemini/IGRINS) in which the coordinator is PI or co-I and multiple state-of-the art codes allowing the forward (SPARC/MITgcm, gCMCRT) and reverse (CHIMERA) modelling of exoplanet atmospheres.