Tidal Oscillations of Rotating Hot Jupiters

Abstract

We calculate small amplitude gravitational and thermal tides of uniformly rotating hot Jupiters composed of a nearly isentropic convective core and a geometrically thin radiative envelope. We treat the fluid in the convective core as a viscous fluid and solve linearized Navier Stokes equations to obtain tidal responses of the core, assuming that the Ekman number ${\rm Ek}$ is a constant parameter. In the radiative envelope, we take account of the effects of radiative dissipations on the responses. The properties of tidal responses depend on thermal timescales $\tau_*$ in the envelope and Ekman number Ek in the core and on weather the forcing frequency $\omega$ is in the inertial range or not, where the inertial range is defined by $|\omega|\le2\Omega$ for the rotation frequency $\Omega$. If ${\rm Ek}\gtrsim 10^{-7}$, the viscous dissipation in the core is dominating the thermal contributions in the envelope for $\tau_*\gtrsim 1$ day. If ${\rm Ek}\lesssim 10^{-7}$, however, the viscous dissipation is comparable to or smaller than the thermal contributions and the envelope plays an important role to determine the tidal torques. If the forcing is in the inertial range, frequency resonance of the tidal forcing with core inertial modes significantly affects the tidal torques, producing numerous resonance peaks of the torque. Depending on the sign of the torque in the peaks, we suggest that there exist cases in which the resonance with core inertial modes hampers the process of synchronization between the spin and orbital motion of the planets.