NONADIABATIC TIDAL FORCING OF A MASSIVE, UNIFORMLY ROTATING STAR .2. THE LOW-FREQUENCY, INERTIAL REGIME

We study the fully non-adiabatic tidal response of a uniformly rotatin g unevolved 2.0-M. star to the dominant l = m = 3, component of the pe rturbing potential of the companion. This is done numerically with a 2 D implicit finite difference scheme. We assume the star is rotating sl owly with angular speed Omega(s) << Omega(c), so that the centrifugal force can be neglected, but the Coriolis force is taken fully into acc ount. We study the low-frequency 'inertial' regime \<(sigma)over bar>\ < 2 Omega(s), where <(sigma)over bar> is the forcing frequency in the frame rotating with the stellar spin rate Omega(s). In this frequency range inertial modes are excited in the convective core which can int eract with rotationally modified g or r modes in the radiative envelop e and cause significant strengthening of the tidal interaction. Resona nt interaction with quasi-toroidal (r) modes in slightly super-synchro nous stars causes efficient spin-down towards corotation. We determine time-scales for tidal spin-up and spin-down in the inertial frequency regime for stars spinning with Omega(s) = 0.1 Omega(c) and 0.2 Omega( c).