Observational and Theoretical Issues of Interacting Binaries was the topic of the 22nd Advanced Course of the Swiss Society for Astrophysics and Astronomy. It was the first time that binary systems were the center of attention of our course. The established concept and organisation of the Advanced Course has been retained: three scientists, all acknowledged experts in their respective fields, were each invited to give nine one-hour lectures within the period of a week. The Advanced Course took place from April 6 to 11, 1992, at Les Diablerets, a charming resort in the Swiss alps. The high level of the lectures, the international background of the 65 participants, including many young students, and the beauty of the surroundings all contributed to the success of the course. The lecture notes of this course, the 22nd in our series, are also the third to be published by Springer-Verlag. Well over half of all stars seem to exist in binary systems. The study of binary evolution is therefore essential for our understanding of stellar evolution in general. The evolution of interacting binaries contains in itself many of the problems met in other fields of modern astrophysics. This is very apparent in these lecture notes.

Peter P. Eggleton and James E. Pringle Institute of Astronomy Madingley Road Cambridge England The 1970's can be described, in retrospect, as the "Decade of the Close Binary". Exciting observations with new technology, combined with classical work, both observational and theoretical, convinced the astronomical world that binary interaction of various kinds is not only interesting but common. Indeed, by 1975 almost anything unusual had a good chance of being interpreted as due to binary interaction. But astronomers are seldom overwhelmed by speculation, even their own, and solid observational work has confirmed or refuted such speculation, without regard to its plausibility. For instance, binarity has been found where it was perhaps least expected, in Barium stars, and refuted where it could most reasonably be expected, in Wolf-Rayets. Unfortunately, many other classes of potential binaries remain without the clearest evidence of binarity, for instance Be stars, symbiotics and blue stragglers. This Advanced Study Institute was held to commemorate John Whelan (1945-1981), whose scientific career, sadly cut short in its prime, did much to further the careful study, theoretical and observational, of close binaries, as well as to encourage the spirit of international friendship and collaboration. His own interests covered a greater field, but "Interacting Binaries" seemed a reasonable restriction. We publish here 15 review talks, which still do not cover the whole topic, although they range widely.

More than two centuries have elapsed since the story of the interacting binary stars began with the rediscovery of the variability of Algol by John Goodricke and the interpretation he proposed for explaining the regular periodic brightness variations which he found. Over this long span of time our knowledge about these systems has been growing, and we have now reached a fairly good understanding of the structure and behavior of this interesting group of objects. This book contains a timely summary of our present knowledge of interacting binary stars. The chapters have been written by distinguished scientists who have done relevant research in the field of interacting binary stars.

This book contains the proceedings of IAU Symposium No. 151 `Evolutionary Processes in Interacting Binary Stars,' which was held from 5 to 9 August 1991 in Cordóba, Argentina. The primary aim of this conference was to review and evaluate our current understanding of the evolutionary processes in wide variety of interacting binary stars from their births to their deaths. Subjects included the formation of binaries, mass flow and transfer, accretion processes, and binaries with collapsed components, such as novae, X-ray binaries and binary pulsars. As the field covered is both broad and diverse, there were in all thirty-seven invited talks; sixty-two contributed papers were also presented. In addition, these proceedings contain comments from a panel discussion of the major unsolved problems of interacting binary stars.

This conference examines the progress in the field of interacting binaries discussing a number of relevant astrophysical problems regarding the interaction between stars in binary systems, such as the physics of neutron stars and black holes that accrete matter from their companion stars and the study of the end points of stellar evolution, like supernovae and gamma-ray bursts. This proceedings provides an updated overview of both observations and theory. Topics include: compact binaries in globular clusters, millisecond binary pulsars, supernovae from massive binary systems and GRBs, accretion on black holes and microquasars, accretion on white dwarfs and novae, rapid variability and secular evolution of LMX-Ray binaries, supernovae type Ia, as well as secular evolution of high-mass x-ray binaries.