CRA Seminar - Characterizing Multi-planet Systems
April 27, 2018 - 3:00pm to 4:00pm
Harvard-Smithsonian Center for Astrophysics
The Kepler mission's census of transiting exoplanets has shown that sub-Neptune size planets with short orbital periods are extremely common. Given their small sizes, the properties of these planets can be difficult or impossible to constrain via radial velocity observations. Mutual gravitational interactions in multi-planet systems cause variations in the arrival times of planets' transits. These variations are a valuable probe for measuring planets' masses and eccentricities, thereby constraining their compositions and formation histories. I will discuss the results of our analysis of the transit timing variations (TTVs) of 145 Kepler planets from 55 multi-planet systems. Some of these multi-planet systems, like Kepler-11, are surprisingly compact and naturally raise the question: just how tightly can a planetary system be packed?
In the second part of my talk I will describe new analytic results for predicting the onset of chaos and instability in systems of two massive, eccentric planets. These analytic results elucidate the role of mean motion resonances in determining orbital stability and serve as a starting point for understanding chaos and instability in higher-multiplicity systems.