Protostellar Disks, Planet Traps, and the Origins of Exoplanetary Systems
With over 800 planets and many planetary systems now known, and over 2000 more candidates waiting in the wings, an unprecedented era for exoplanetary science has just begun. The data increasingly show the presence of a number of distinct planetary populations; hot Jupiters in close (few day) orbits around their host stars, a large population of more massive Jupiters at a few AU, a rapidly expanding population of SuperEarths, and finally a population of more massive planets at large radii (~ 50-100 AU) discovered through direct imaging studies. The observed mass-period relation for exoplanets provides many challenges for theoretical models of planet formation and migration. In this talk, I will survey some of these important new results and theoretical models. I will then focus on our own work (with Yasuhiro Hasegawa) on the role of inhomogeneities in protostellar disks which serve as "planet traps" - regions in which it is particularly favourable to grow planets and to drastically slow their rapid inward migration through their natal gaseous disks . I will show how planetary accretion and the motion of traps in evolving disks can naturally explain aspects of these recent surveys.