Abstract:  Studying the present day architectures and dynamics of high-multiplicity (N ≥ 3) exoplanetary systems provides a unique avenue for probing the astrophysics of planet formation and for constraining exoplanet demographics. Here, I present a new framework for characterizing the arrangements of masses, periods, and mutual inclinations within such systems. I demonstrate that Kepler’s high multiplicity systems can be explained if most systems belong to a single intrinsic population, with a subset of systems hosting additional, undetected planets. I further demonstrate that planets within a system tend to be evenly spaced in log-period and roughly the same size, and that these trends are astrophysical in nature and not an artifact of observational biases. Conclusions regarding planetary inclinations and eccentricities are less clear and require improved transit lightcurve fits to allow for robust inferences. However, accurate transit modeling is confounded by both instrumental and asteroseismic noise, as well as by unresolved transit timing variations (TTVs) and transit duration variations (TDVs) which arise from gravitational interactions between neighboring planets. To remedy this problem, I am currently reprocessing all (~3300) Kepler lightcurves for stars known to host planet candidates. I employ all available short cadence data, using a technique that simultaneously models noise with a Gaussian Process (GP) regression and accounts for both TTVs and TDVs with an optimally flexible parametric model. These timing measurements can be inverted using dynamical models to produce a large statistical sample of planetary masses, filling out the mass-radius diagram. This project will yield the highest-fidelity measurements of TTVs and TDVs produced to date, as well as dramatically improved constraints on planetary inclinations and eccentricities. In the near future, I will extend these methods to every planetary candidate observed by Kepler, K2, and TESS, with an expected yield of nearly 100 previously undetected TTVs/TDVs.

Host:  Rebekah Dawson/Dan Stevens

Please click the link to join the webinar: https://psu.zoom.us/j/96060188956