Tidal evolution of eccentric orbits in massive binary systems

II. Coupled resonance locking for two rotating main sequence stars

Astronomical Institute "Anton Pannekoek", University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands

Corresponding author: M. G. Witte, marnix@astro.uva.nl

Received: 8 September 2000
Accepted: 13 November 2000

Abstract

We extend our study of the tidal evolution of elliptic binary systems to the case of a system consisting of two uniformly rotating main sequence stars. Previous work showed that in a system consisting of a compact object in orbit about a main sequence star stellar oscillation modes were prone to be excited nearly resonantly for prolonged periods of time. This resonance locking was shown to constitute an effective mechanism for orbital decay in moderately eccentric orbits. In this work we investigate in what ways the locking mechanism is altered if also the companion is tidally perturbed, also inducing orbital changes and potentially also being locked in resonance. We show that simultaneous locking can intensify the tidal excitations, and that resonance locking is a common phenomenon during the tidal evolution of eccentric double main sequence binary systems which speeds up the secular evolution significantly.