Chris Ormel - March 24, 2017

Recent advances in Planet Formation

The past two decades have seen major exoplanet milestones. These
include hot-Jupiters orbiting their host stars in several days,
super-Earths and mini-Neptunes -- planets made up mostly of heavy
elements, but often inferred to contain significant amounts of
primordial (H/He) gas -- and very compact systems that may harbor
rocky planets in the so-called habitable zone.  Clearly, the
architectures of exoplanetary systems is very different from the
solar system, which raises the (formidable) question where in its
history planetary systems started to diverge.
Here, I will focus on planet formation: the process that operated
during the first couple of million years in the presence of a
H/He-rich disk.  Our classical ideas on how planets form are,
however, tailored to the solar system and may be inadequate to
explain exoplanetary systems.  As I will explain, classical formation
theory is a purely local theory, where modern concepts like planet
migration or pebble drift do not play a role.  After reviewing the
classical theory, I will discuss some recent developments of my group
that attempt to reconcile modern planet formation theory with
observational constraints: planetesimal formation around snowlines,
pebble accretion, disk-planet atmosphere recycling, and
star-disk-planet magnetic coupling.