The Chair focuses on all aspects of the formation and evolution of planetary systems. Since the discovery of numerous extrasolar planets (planets orbiting stars other than the Sun) from 1995 onwards, it has become apparent that the structure of our own solar system is atypical, and that extrasolar systems can also exhibit great diversity among themselves. This unexpected observation makes understanding the origin of such diversity a major challenge in planetology. The various aspects of planetary formation and evolution addressed in this Chair are centered around this question.
Compared with extrasolar systems, for which observational knowledge is partial and limited at best to the masses, radii and orbits of the main planets, our solar system provides us with a large number of constraints that enable us to accurately reconstruct its history. In addition to the planets and their overall characteristics, we know the distribution of small bodies such as asteroids, comets, trans-Neptunian objects, satellites and trojans. These bodies are the remnants of the first objects known as planetesimals , which initiated planetary formation. Their orbital distributions and physical characteristics constitute a fossil record of the early dynamical evolution of planets in formation. In addition,thanks to meteorite analysis (natural samples of asteroids), in situmeasurements (e.g. of comet 67P/Chourioumov-Guérassimenko by the European Space Agency's Rosetta mission) and remote spectroscopic measurements, we have in-depth knowledge of the chemical and isotopic compositions of the various small bodies. This information provides insight into the structure of the protosolar disk, as well as the circulation and partial mixing of dust within it. By comparing these properties with those of the planets, we can deduce the origin of the matter that composes them. Certain isotopic systems also provide us with information on the chronology of the formation of small bodies, the synthesis of their constituent minerals and the accretion of planets.
The approach of this Chair is based on exploiting this wealth of information to better understand the processes that gave rise to our solar system and our Earth in particular. This knowledge will then be applied to the general context of planetary formation, enabling us to explore the variety of possible evolutionary trajectories and compare the systems thus produced with known extrasolar systems.
