Non - adiabatic tidal forcing of a massive , uniformly rotating star II : The low frequency , inertial regime

We study the fully non-adiabatic tidal response of a uniformly rotating unevolved 20M ⊙ star to the dominant l = m = 2 component of the companion's perturbing potential. This is done numerically with a 2D implicit finite difference scheme. We assume the star is rotating slowly with angular speed Ω s ≪ Ω c , so that the centrifugal force can be neglected, but the Coriolis force is taken fully into account. We study the low frequency 'inertial' regime |σ| < 2Ω s , where σ is the forcing frequency in the frame rotating with the stellar spin rate Ω s. In this frequency range inertial modes are excited in the convective core which can interact with rotationally modified g-or r-modes in the radiative envelope and cause significant strengthening of the tidal interaction. Resonant interaction with quasi-toroidal (r-)modes in slightly super-synchronous stars causes efficient spin down towards corotation. We determine timescales for tidal spin-up and spin-down in the inertial frequency regime for stars spinning with Ω s = 0.1Ω c and 0.2 Ω c .