Synchronization in binary stars

Abstract

Radiative dissipation of the dynamical tide is found to be inadequate in explaining the observed synchronization between orbital and rotational motions of the main sequence components of early-type binary stars. The rotational behaviour of binary components suggests the possible existence of two sequences of binary stars of which one is synchronous even at large separation between the binary components. The primaries of Algol systems are not found to behave any differently from detached binaries thereby nagating any evidence for large scale angular momentum transfer in the recent past. The rotational behaviour of binary components is analogous to the bimodal rotational velocity distribution of main sequence signal stars. We argue that the members of the synchronous sequence posses high subsurface magnetic field strengths which extend their main sequence lifetime considerably.