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CORDIS - Resultados de investigaciones de la UE

Atmospheres across the Universe

Periodic Reporting for period 4 - ATMO (Atmospheres across the Universe)

Período documentado: 2022-08-01 hasta 2023-07-31

Which molecules are present in the atmosphere of exoplanets? What are their mass, radius and age? Do they have clouds, convection (atmospheric turbulence), or a circulation induced by irradiation? These questions are fundamental in exoplanetology to better understand planet formation and exoplanet habitability with the James Webb Space Telescope (JWST).

This project aims at characterizing the impact of diabatic convection (i.e. with source terms) in the atmosphere of stars, brown dwarfs, and exoplanets and its interaction with the circulation in the case of irradiated planets. By developing innovative numerical models, we will characterize the effect of the diabatic instability induced by chemical transitions (e.g. CO/CH4) with radiative transfer and its interaction with the global circulation in the atmosphere. We will then predict and interpret the mass, radius, and chemical composition of exoplanets that will be observed with future missions such as the JWST.

Thermo-compositional diabatic convection is a new concept proposed in Tremblin et al. 2019 that encompass several well known convective systems in which source terms are important (thermohaline convection in Earth oceans, fingering convection in stars, moist convection in Earth atmosphere, steam/liquid water convection in cooling systems, and CO/CH4 radiative convection in the atmosphere of brown dwarfs and extrasolar giant exoplanets).
- We have developed a massively-parallel convection code called ARK that has been used to perform “grand challenge” simulations on the entire GPU supercomputer Jean Zay and Adastra in France. The code is publicly available at
- We have performed 3D simulations of the circulation of the atmospheres on Hot Jupiters on 1000 years, showing that on these long timescales, the deep atmosphere becomes hot. This fully confirms our theory for the explanation of the “radius inflation puzzle”, an astrophysical problem that has not been explained for 20 years.
- We have developed a full theoretical framework to study CO/CH4 convection in brown dwarfs. It turns out that it exceeds by far the problematic of the ERC: we have shown that thermohaline and moist convection in Earth atmosphere and oceans can also be described by our general theory, and it opens new perspectives in the understanding of these convective phenomena. It could also be used to understand complex behaviour such as the “boiling crisis” in the cooling systems of nuclear power plants (a subject that is of interest for CEA which is the French nuclear research lab).
The theory of diabatic convection is a major achievement in the understanding of convective processes. We have extended the theory to include shear flows and also magnetized flows and we have studied the generation of magnetic fields by convective dynamos on the largest supercomputer in France. The theory can then be used to understand differential rotation and the generation of magnetic fields in the Sun and stars. Sheared convection can also be used to study the formation of jets in planetary atmospheres.
Visualization of the density in the "grand challenge" simulation of CO/CO2 diabatic convection