Abstract

For centuries, planet formation theories were fine-tuned to explain the details of solar system. The diversity of planetary systems uncovered by Doppler surveys challenged previous theories and led to insights into planet formation, orbital migration and the excitation of orbital eccentricities and inclinations. NASA ’s Kepler mission has identified 450 systems with multiple transiting planet candidates, thousands of planet candidates and many small and potentially rocky planets. I will discuss how the planets identified by Kepler are enabling scientists to characterize the distribution of planetary properties and the architectures of planetary systems. In particular, transit timing variations (TTVs) provide an excellent tool to characterize the masses and orbits of dozens of small planets, including many at orbital periods beyond the reach of both Doppler surveys and photoevaporation-induced atmospheric loss. Dynamical modeling of these systems has identified some “super-puffy” planets, i.e., low mass planets with surprisingly large radii and low densities.

I will describe a few particularly interesting systems and discuss the implications for the super-puffy planets. These systems and Kepler’s other discoveries are inspiring a new wave of planet formation theories attempting to explain new populations of systems with tightly-packed inner planets (STIPs), and intricate orbital resonances. I survey recent efforts to translate Kepler discoveries into constraints on the formation and orbital evolution of planetary systems.