Jeremy Leconte - March 23, 2018

A new vision of the interiors and atmosphere of gas giant planets and 
brown dwarfs. 


Many unknowns remain concerning the internal structure and composition of giant
gaseous planets, even in our own Solar System. The existence and the properties
 of an hypothetical central core, in particular, are still debated. But for a 
long time, this debate mostly revolved around the uncertainties in the 
thermodynamic properties of the gases involved. 
While it was hypothesized that the composition of the gaseous envelope of these
 planets could be inhomogeneous, the dynamical implications of this 
inhomogeneity on the mixing and energy transport have not been investigated 
until recently. However, it is well known from the study of our ocean that a 
gradient of salt concentration - and the resulting density gradient -  can slow
 down, or even completely suppress convection.
In this seminar, I will discuss how a gradient of helium and/or volatiles can 
affect the onset and efficiency of convection in the atmosphere and the deep 
interior of gas giant planets and the potential implications for our 
understanding of their volatile content. I will further discuss whether these 
processes can help explain some yet unexplained features of brown-dwarfs 
spectral-type transitions.