Wednesday, September 28, 2011 - 3:00pm
Yasuhiro Hasegawa (McMaster):
"Theory of planet traps"
Abstract. Planetary migration has begun to be recognized as one of the origins of diversity of observed extrasolar planets (currently over 600). One of the longstanding problems in theories of planet formation is that rapid planetary migration arises from tidal, resonant interactions between protoplanets and their host gaseous disks. Planetary migration is highly sensitive to disk properties such as disk surface density and temperature, so that, without a large number of Monte Carlo based simulations, it is difficult to derive the predominant cause of their diversity. In this talk, we will discuss the idea of planet traps that capture bodies undergoing type I migration. Planet traps, that are the product of disk inhomogeneities, enable us to understand the role of planetary migration in a statistical sense. I will start from a simple physical argument in order to examine how sensitive the tidal torque is to disk properties. This argument gives insight into why disk inhomogeneites are required for the presence of planet traps. As an example, we focus on our newly discovered heat transition trap where the major source of disk heating switches from viscous to radiative heating. If time remains, I will also discuss the movement of planet traps as disks evolve which is important for understanding the diversity of observed planetary system architectures.