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Building the next generation of planet formation models: protoplanetary disks, internal structure, and formation of planetary systems

Final Report Summary - PLANETOGENESIS (Building the next generation of planet formation models: protoplanetary disks, internal structure, and formation of planetary systems)

The understanding of the origin, nature and evolution of planets, both in our Solar System, and around other stars is probably one of the most exciting and challenging problem of modern astronomy, and science in general, since it involves interaction with many other scientific fields, from geology to prebiotic chemistry. The understanding of the process of planet formation is however hardly observable, since planets form in protoplanetary disks, where large gas and dust opacity prevents direct observations. Model must therefore be developed in order to interpret and put in context observations from two different classes of astronomical objects, located on both side of the global planet formation process. On one side, protoplanetary disks (the birthplace of planets) are observed with more and more details, thanks to new observatories like e.g. the Atacama Large Millimetre/submillimetre Array (ALMA). On the other side, more and more extrasolar planetary systems are presently detected and characterized thanks to Earth based and space based observatories, using a variety of detection methods, like radial velocity (e.g. the ESO/HARPS spectrograph), or transit observations (e.g. NASA/Kepler Mission, ESA/CHEOPS mission, ESA/PLATO project…). The goal of the PLANETOGENESIS project, conducted by Prof. Yann Alibert from the University of Bern, was to develop our theoretical understanding of planet formation and evolution, by developing theoretical models that, starting from observations of protoplanetary disks, allow to explain and predict properties of extrasolar planetary systems, like their orbital characteristics and bulk composition.
PLANETOGENESIS consisted in three research directions. The first direction is the better theoretical modelisation of protoplanetary disks, and includes the computation of the heating effect by the parent star of the planetary system, and the effect of gravitational interactions between planets in formation and gas and solids making the disk. The second direction is related to the determination of the internal structure of planets, including complex effects like pollution of the planetayr envelope by accreted solids.
Finally, the last direction is related to the interactions between planets forming in the same planetary system, which consist mainly in the gravitational interactions between planets, and the competition for gas and solid capture by these planets (planets acquire their mass by capturing gas and solids originating from the protoplanetary disk, such a competition has profound effect on the resulting structure of planets).