The formation of planetary systems

Our own Solar System formed a little over 4.5 Gyr ago from a cloud of gas and dust. As the sun was forming at the centre of the system, planets and minor bodies of the solar system assembled from the leftovers of this process. The architecture of our system and the physical and chemical properties of its constituents provide clues of the condition and processes at work in that remote era. We also know that planetary systems are very common around stars in our own galaxy, this implies that the process of planet formation is a robust one. Nonetheless, the majority of the known exo-planetary systems have a very different architecture than our own. The study of stars and planetary systems in formation today in the solar neighborhood allows us to constrain the physical and chemical conditions for the formation of planets. In this talk I will discuss our current understanding of the process of planet formation. I will discuss the current evidence for the growth of solids in protoplanetary disks towards the formation of the rocky cores of planets.

I will discuss the theoretical difficulties we have in explaining this process and how new observations are providing us with essential data to solve the long standing ‘meter size’ barrier paradox. Observations with the Atacama Large Millimetre/submillimetre Array are also allowing us to quantitatively probe the evolution of the volatile component of protoplanetary disks, at the origin of planetary atmospheres. I will discuss our current understanding of the chemical evolution of disks, at the origin of the different planetary atmospheres and of complex organic molecules observed in the pristine bodies of our own solar system.