Abstract
In this dissertation, we study the interaction of stars in binary systems and the remnants they leave behind. Binary systems play an important role in stellar evolution, the stars within them influence each other through mass transfer and tides, they often host massive stars that explode as supernovae, and they may lead to high-velocity ejections. Moreover, they are ideal laboratories for studying accretion disks. Improving our understanding of these systems is vital and is the main aim of this thesis.
We study the process of mass transfer in systems where the donor star rotates either more slowly or faster than the rotation of the orbit. We find that mass streams from sub-synchronous donors approach the accretor much closer than in the synchronous case, and that self-accretion always synchronises the donor with the orbit. In populations of inter-acting binaries with main-sequence accretors, we find that disk mass-transfer may play a significant role, but since many of these systems transfer mass with sub-synchronous donors, taking into account the asynchronous effects on the mass stream is likely to reduce this importance.
Based on detailed stellar models, we improve the tidal interaction between binaries and compare synthetic populations with observations of binaries in open clusters. While the improved models have little effect on the eccentricity distributions, they do lead to more synchronised binaries.
We also study the formation of binary black hole mergers and compare our results with observations. We find that the tentative feature at 35 M is unlikely to be caused by the pulsating pair-instability supernovae and must therefore be caused by other (binary) interactions. Moreover, these high-mass black hole systems are formed mainly either by stable mass transfer or by merging without interaction due to the supernova kicks at the formation of the black holes.