Planet formation and evolution: key processes to understand the diversity of planetary systems
by
Alessandro Morbidelli(Observatoire de la Cote d'Azur)
→
Europe/Stockholm
Description
The discovery of a large number of extrasolar planets has demonstrated
that our own system is not "typical". Exo-planetary systems can be
very different from our own, and diverse from each other.
Understanding this diversity is a major goal of modern planetary
science.
The formation of planetary systems is not fully understood, but major
advances have been obtained in the last 10 years. New concepts have
been proposed, such as the streaming instability for the formation of
planetesimals and pebble accretion for the formation of protoplanets.
It is also now clear that planets forming in the proto-planetary disks
have to migrate during their accretion, if their mass exceeds a few
times the mass of Mars. Accretion and dynamical evolution are
therefore very coupled processes. This leads to complex evolutions,
very sensitive to initial conditions and fortuitous events, that are
the key to understand the observed diversity of planetary systems. The
early formation of Jupiter and its limited migration due to the
formation of Saturn are two fundamental ingredients that determined
the basic structure of the Solar System. The lack of early formation
of giant planets typically leads to the formation of super-Earth
planets on short period orbits. There is also evidence that the vast
majority of planetary systems become unstable after the removal of the
protoplanetary disk. The effects of this instability are very
different depending on the masses of the planets involved. Our Solar
System also experienced a global instability, but fortuitously our
giant planets did not develop large orbital eccentricities.