A Past Episode of Rapid Tidal Evolution of Enceladus?

Saturn possesses a dynamically rich system containing numerous moons and impressive rings. Whether the rings of Saturn are much younger than the planet itself has been a long-open question; more recently a young age has been proposed for some moons. Recent detection of the fast orbital evolution of Rhea and Titan strongly suggest highly frequency-dependent tidal response of Saturn, possibly through excitation of inertial waves within the planet's convective envelope. Taking into account observations and numerical simulations, we argue that nether pure evolution through inertial waves not conventional (equilibrium) tides can explain the Saturnian system. We propose that the system's architecture can best be explain by relatively high "background" tidal response coupled with discrete resonant modes. Assuming that Enceladus went through a temporary period of fast tidal evolution, we can reproduce its present resonance with Dione and satisfy other dynamical constraints.

Speaker: Matija Cuk, SETI