Institute for Advanced Study Astrophysics Seminar

High-eccentricity migration is a possible formation channel for hot Jupiters. However, in order for it to be consistent with the observed population of planets, tides must circularize the orbits in an efficient manner. In this talk, I will discuss how nonlinear mode interactions in the planet can enhance the efficiency of tidal circularization. In particular, nonlinear mode interactions can trigger tides in the planet to experience a phase of diffusive growth when the orbit is highly eccentric. When the diffusive growth happens, the semi-major axis can shrink by a factor of nearly 10 over 10 kyr, corresponding to a tidal quality factor of Q~10. Such rapid orbital circularization naturally explains the observed paucity of super-eccentric proto-hot Jupiters in Kepler's data. While previous studies considered triggering the diffusive growth by tidal back-reaction, I will show that nonlinear interactions are in fact the dominant source of diffusion. Incorporating nonlinear interactions could thus expand the parameter space that allows the diffusive growth to happen and consequently enhance the formation rate of hot Jupiters through the high-eccentricity migration channel. It could further mitigate the discrepancy between the observed and predicted occurrence rates for close-in gas giants as compared to those further from the star. Lastly, I will discuss a few outstanding questions that remain to be addressed before we can obtain a complete understanding of the tidal migration channel.

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