Soutenance de thèse de Francesca Miozzi

Francesca Miozzi, doctorante dans l'équipe Minéralogie, pétrologie et physique planétaire (MP³) soutient sa thèse le mercredi 3 Juillet 2019 à 14h30 dans la salle de conférence de l'IMPMC (campus Jussieu, Tour 23, couloir 23-22, 4ème étage, salle 401).

Experimental study of the Fe-Si-C system and application to carbon rich exoplanets

Abstract

More than 4000 exoplanets have been discovered, orbiting around stars with a wide variety of composition. Such planets are detected and studied through indirect methods that in many cases give access to the main properties of the planets: mass and radius. The same parameters can be calculated from a chosen model and compared to the observed ones. However it is difficult for planets orbiting around stars with compositions very different from our Sun, for example carbon enriched, as the physical properties carbides (i.e. silicon carbides and iron carbides) at extreme pressure are unknown. In this work the Si-C and Fe-Si-C systems were studied in the range between 20 and 200 GPa and 300-3000 K employing X-ray diffraction and chemical analyses on the recovered samples were used to determine the physical properties at extreme conditions. In the Si-C system the equations of state and thermal model for both the low pressure and high pressure phases were determined. The results were then used to model a mass radius plot for different archetypal planets with a Fe core and SiC mantle. Regarding the Fe-Si-C system a ternary phase diagram was reconstructed up to 200 GPa and 3000 K. Assuming Fe-Si-C as main component of planetary cores, four different crystallization paths are individuated, giving rise to way different dynamical behaviour. We conclude that using only mass radius relations is not sufficient to determine the interior composition and structure of an observed exoplanet and further data relative to the chemistry are needed, for example the composition of the host star.

Jury

• M. James Badro (Rapporteur)
• Mme. Anat Shahar (Rapporteuse)
• M. Pierre Beck (Examinateur)
• Mme. Chrystèle Sanloup (Examinatrice)
• M. Sebastien Merkel (Examinateur)
• Mme. Giovanna Tinetti (Examinatrice))
• M. Guillaume Morard  (Directeur de Thèse)
• M. Guillaume Fiquet (Co-directeur de Thèse)