PhD defense by Artem Aguichine

“Retracing the fate of volatile compounds: from circumstellar disks to planetary interiors“

zoom: 
https://univ-amu-fr.zoom.us/j/89671630809?pwd=Q2Jhbkd5cWZHU3VuS3lyVUVrWGhyQT09

Abstract:

Volatile compounds are a part of the elementary blocks in planet formation, and are also essentials for the formation of life. Understanding how they are redistributed in protostellar disks gives valuable information on planet formation mechanisms, which can then be used to assess the habitability of (exo)planets. The work I have done aims to create numerical models of physical phenomenons at the planetary scale to explain observations.

I have developed a numerical model of the protosolar nebula (PSN), that simulates its radial evolution (1+1D model) in time. This model solves numerically the equation of motion in the radial direction of the H2-He cloud in the alpha-viscous disk formalism. This model then solves the equation of radial transport of volatile and refractory compounds, including phase transitions between pure ices and vapors. Since planets are formed from matter present in the PSN, a comparison between the results of my model and observational data produces constraints on the time and location of formation of various bodies of the solar system.
In planetary interiors, matter is at extreme pressures and temperatures, very different from that in the PSN. I implemented several new physical phenomenons to a pre-existing planet interior structure model to extend its working range to irradiated ocean planets (IOP). This extended model allows to estimate the possible water content in exoplanets, for which spectroscopic data is lacking. Some compositions are excluded, because their hypothetical water envelopes would be unstable in light of atmospheric escape mechanisms. The remaining, stable, planets form a population of candidates for habitable worlds.

Jury members:

Anders JOHANSEN, University of Copenhagen – Referee
Thibault CAVALIÉ, Laboratoire d’Astrophysique de Bordeau – Referee
Jonathan I. LUNINE, Cornell University – Examiner
Pierre VERNAZZA, LAM – Examiner
Ravit HELLED, University of Zurich – Examiner
Magali DELEUIL, LAM – President

PhD supervisor:

Olivier MOUSIS, LAM