On Synchronization in Detached Close Binaries: Reply to Rieutord and Zahn

摘要

In this paper we discuss the tidally driven meridional currents that spin down (or spin up) a nonsynchronous rotator in a time that is much shorter than the viscous decay time of residual motions. We refute the claim made by Rieutord & Zahn, who have argued that this large-scale meridional flow does not exist, so that the synchronization time should remain larger than the viscous time in a tidally distorted body. To be specific, they describe the internal motion by means of a series in the powers of the small parameter δ/R, which is the relative thickness of the Ekman boundary layer at the free surface.