PhD Defense by Lorena Acuna

“Modelling the populations of low-mass planets: transition between super-Earths and mini-Neptunes”

Zoom link:
https://univ-amu-fr.zoom.us/j/88020777410?pwd=WlNQL1VyYWxOQjFaQ1pnU0I3SUpPdz09

Abstract
Low-mass exoplanets are showing a diversity in their densities and irradiation conditions, ranging from highly irradiated planets to temperate worlds. To estimate their composition, we have developed an interior structure model that includes self-consistently an
atmosphere in radiative-convective equilibrium. The model can accommodate
water and CO2 envelopes under the extreme conditions of highly-irradiated
exoplanets, which are the most numerous population. It can be used as a forward model to generate mass-radius relationships, as well as within our own Bayesian adaptive Markov Chain Monte Carlo (MCMC), which estimates the uncertainties of the compositional parameters given the error bars of the observed mass and radius. We present the various
developments we carried out to achieve the coherent implementation of
the coupled interior and atmosphere model and its validation. The applications of the model are the estimation of the compositional parameters with their respective uncertainties based on observations
for a single planet, the analysis of planetary compositions within
multiplanetary systems to constrain their formation mechanisms, and
the assessment of the observability of emission spectra for rocky
exoplanets with the James Webb Space Telescope (JWST). Already used to analyze
the composition of a large sample of exoplanets, we discuss the
compositional properties of this sample, as well as the limitations due
to uncertainties and degeneracies the model faces. Our model may serve as a precedent of a modelling framework built to interpret mass, radius and atmospheric characterization data provided by upcoming missions such as PLATO and Ariel.

Jury members:
Jean-Luc BEUZIT, LAM – President
Pierre DROSSART, IAP/PSL/LESIA – Referee
Giovanna TINETTI, University College London – Referee
Jérémy LECONTE, Laboratoire d’Astrophysique de Bordeaux – Examiner
Emmanuel MARCQ, UVSQ/LATMOS – Examiner
Heike RAUER, Freie Universität Berlin – Examiner
Laura KREIDBERG, Max Planck Institute for Astronomy – Invited
PhD supervisor:
Magali DELEUIL, LAM
PhD co-supervisor:
Olivier MOUSIS, LAM