The Project

   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 JWST.

« James Webb Space Telescope will tell us more about the atmospheres of extrasolar planets, and perhaps even find the building blocks of life elsewhere in the universe. »

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/CH\(_4\)) 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 James Webb Space Telescope (JWST).

What is diabatic convection?

    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/CH\(_4\) radiative convection in the atmosphere of brown dwarfs and extrasolar giant exoplanets).

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“Paleo-climate” simulation of Hot Jupiters

By adapting the 3D general circulation model DYNAMICO developed at LSCE to the study of exoplanets, we have shown that the unexplained radius inflation of Hot Jupiters is the result of the long timescale meridional circulations that heat up the deep atmosphere. Thanks to the increased performances of the code and by using low resolutions (similarly …

A general theory for adiabatic and diabatic thermo-compositional convection

By generalizing the theory of convection to any type of thermal and compositional source terms (diabatic processes), we show that thermohaline convection in Earth oceans, fingering convection in stellar atmospheres, and moist convection in Earth atmosphere are deriving from the same general diabatic convective instability. We show also that ”radiative convection” triggered by CO/CH4 transition …

Pre-ERC result: Hubble Detects Exoplanet with Glowing Water Atmosphere

Image © NASA, ESA, and A. Feild (STSci) Exeter University Press release: Scientists have found unmistakable evidence for a stratosphere on an enormous planet outside our solar system, with an atmosphere hot enough to boil iron. An international team of researchers, led by the University of Exeter, made the new discovery by observing glowing water molecules in …

Contact and Team


  • Pascal Tremblin: Personal Website
  • Phone: +33 1 69 08 59 67
  • Email: pascal.tremblin[at]


  • Felix Sainsbury-Martinez, Astrophysicist (Postdoc)
  • Simon Daley-Yates, Astrophysicist (Postdoc)
  • Solène Bulteau, Mathematician (Postdoc)
  • Mathilde Poveda, PhD student
  • Hélène Bloch, PhD student (funded by CEA)
  • Thomas Padioleau, PhD student (funded by CEA)
  • Rémi Bourgeois, PhD student (funded by CEA)

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