Institution(s): 1. Massachusetts Institute of Technology
We study the orbital evolution of hot Jupiters due to the excitation and damping of tidally driven g-modes within solar-type host stars. Linearly resonant g-modes (the dynamical tide) are driven to such large amplitudes in the stellar core that they excite a sea of other g-modes through weakly nonlinear interactions. By solving the dynamics of large networks of nonlinearly coupled modes, we show that the dissipation rate of the dynamical tide is several orders of magnitude larger than linear theory predicts. As a result, we find that the orbits of planets with mass Mp > MJ and period P ~ 2.5, 2.0, and 1.5 days decay on timescales 6, 1.5, and 0.2 Gyr, respectively. This corresponds to stellar tidal quality factors Qstart ~ 105-106. Furthermore, planets with Mp < MJ can also have short decay timescales if they have extremely short periods. We find that the orbits of several known systems, including WASP-19b and HAT-P-36-b, decay on timescales shorter than 0.1 Gyr. Rapid, tide-induced orbital decay may explain the observed paucity of planets with Mp > MJ and P < 2 days around solar-type hosts and could generate detectable transit-timing variations in the near future.