Tidal torque balance in stars and gaseous planets

Tidal torques can alter the spins of tidally interacting stars and planets, usually over shorter timescales than the tidal damping of orbital separations or eccentricities. Simple tidal models predict that in eccentric binary or planetary systems, rotation periods will rapidly evolve toward a “pseudosynchronous” ratio with the orbital period. However, this simple prediction does not account for “inertial” waves that are intrinsic to stars and gaseous planets with (i) convective regions and (ii) even very slow rotation (inertial oscillations have recently been detected in our own Sun). I will describe new results demonstrating that tidal driving of inertial oscillations in eccentric systems can counterbalance the equilibrium tidal torque at numerous ratios of orbital to rotation period that can deviate significantly from the pseudosynchronous prediction. By introducing a network of easily predictable period ratios at which the total tidal torque vanishes, inertial oscillations may impede the process of spin pseudosynchronization in low-mass stars and gaseous planets with convective envelopes.