Deciphering Kepler's Planetary Systems

The theory for how planetary systems form and achieve their final configuration remains highly uncertain, both because of theoretical uncertainties, and because until now theories could only be tested against a single system -- the solar system. The Kepler mission, with its abundance of planetary systems, will likely prove to be a Rosetta stone. However, much remains to be deciphered. To fully realize the potential of the Kepler mission, one must identify the patterns underlying the diverse Kepler systems and develop theories to explain these patterns. This proposal consists of two complementary tasks. Task 1: Characterizing the Kepler systems. We will use observed transit-time-variation (TTV) signatures to measure masses and orbits of Kepler planets, employing our newly derived simple analytical expressions. We will extend our expressions to treat other TTV effects, including higher-order resonances and three body resonances. We will apply these formulae not only to individual Kepler planets, but also to the ensemble of planets, taking advantage of the sheer number of observed planets to uncover the underlying statistical distributions and correlations hiding beneath noise. We hope thereby learn as much as possible about the Kepler planets' properties. Task 2: Modelling the formation of Kepler systems. We plan to reverse engineer these systems by simulating environments that could have led to their observed orbital characteristics. Our recent work on resonant repulsion implies that Kepler systems experienced prolonged dissipation in the past. We will examine whether prolonged dissipation is consistent with all of the planets' observed properties, and what it teaches us about how the planets achieved their current orbits. Finally, we will push back to earlier times to learn about even earlier stages in the process of planet formation.