Y. Kondo - Böcker

More than two centuries have elapsed since the story of 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 behaviour 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 Cordoba, Argentina. The primary aim of this conference was to review and evaluate current understanding of the evolutionary pocesses in a wide variety of interacting binary stars from their births to their deaths. Subjects include 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 37 invited talks; 62 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 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 Cordoba, Argentina. The primary aim of this conference was to review and evaluate current understanding of the evolutionary pocesses in a wide variety of interacting binary stars from their births to their deaths. Subjects include 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 37 invited talks; 62 contributed papers were also presented. In addition, these proceedings contain comments from a panel discussion of the major unsolved problems of interacting binary stars.

The proceedings of the XXVIIth ESLAB symposium presents a comprehensive review of the status of astrophysics and cosmology today. The book provides an insight into the current and future fundamental problems which will be addressed by scientists in the 21st century. The accomplishments of the golden decades, in which many new observing windows have been opened to all astronomers through space exploration, the 4-metre class ground telescopes and interferometric techniques at radio wavelengths, are highlighted concisely. The state of our theoretical understanding of the Universe, extending from the nearby interstellar medium (the Solar Bubble) out to the very early stages of the Universe, and the importance of gravitational lenses are illustrated in lucid reviews. A set of colour pictures from recent experiments illustrates the future of observational astronomy.The reviews are comprehensive and are at a level suitable for professional astronomers who want to remain informed about the fields beyond their specialties, for students at graduate and undergraduate level, as well as for decision makers who need to understand the importance of the scientific challenges which will require support in the future.

IAU Symposium No. 168, examining the Big Bang and diffuse background radiations, took place on August 23-26, 1994 at the XXIInd IAU General Assembly in the Hague, Netherlands. The meeting attracted a large number - over 250 - of astronomers, reflecting the strong interest engendered by the great advances in cosmology made in recent years. There is still a multitude of unresolved problems in modern cosmology and the symposium offered a wonderful occasion to examine them objectively, at a place where many leading workers in related fields gathered together. After the introduction by IAU President L. Woltjer and the historical background by Vice Present Virginia Trimble, the volume begins with reviews of the cosmic microwave radiation from COBE (Cosmic Background Explorer). Reviews of recent observations then extend from radio to infrared, visible light, ultraviolet, X-rays and gamma-rays. It is followed by theoretical models for the Big Bang and inflation, and alternative views to the Big Bang. Following a discourse on "Probes and Future Tests", the meeting ended with a panel discussion on "Major Unsolved Problems of Cosmology".Contributed papers - both oral and poster reports - are included after the invited talks and panel discussions.

Recent advances in observational and theoretical efforts in understanding the nature of cataclysmic variables had reached such maturity that there existed a strong, shared feeling among the workers in this field that an international colloquium sponsored by the International Astronomical Union would be timely. To be more specific, this was due primarily to the accumulation of the new data from satellite observatories, such as the International Ultraviolet Observatory (IUE) and EXOSAT, as well as ground-based optical and radio telescopes, and the advances in modeling the putative accretion disks and the thermo-nuclear run-away phenomena in the vinicity of the white dwarf stars in cataclysmic variables. A series of workshops on this subject held in North America over the past several years and that held in Europe in 1985 had all contributed to the advances in our knowledge that led to IAU Colloguium No. 93, held in Bamberg from the 16th to 19th of June 1986. In all, 157 astronomers from 27 countries participated in this conference. Judging from the papers presented, both invited and contributed, and from the enthusiasm seen in discussions, the meeting was indeed a success.

ROSAT Observations G. HASINGER Max-Planck-Institut flir extraterrestrische Physik, D-85740 Garching, Germany Abstract. This review describes the most recent advances in the study of the extragalactic soft X-ray background and what we can learn about its constituents. The deepest pointed observations with the ROSAT PSPC are discussed. The logN-logS relation is presented, which reaches to the faintest X-ray fluxes and to the highest AGN surface densities ever achieved. The N(>S) relation shows a 2 density in excess of 400 deg- at the faintest fluxes and a flattening below the Einstein Deep Survey limit. About 60% of the extragalactic background has been resolved in the deepest field. Detailed source spectra and first optical and radio identifications will be discussed. The results are put into perspective of the higher energy X -ray background. Key words: X-rays, background radiations, active galactic nuclei. 1. Introduction The extragalactic X-ray background (XRB), discovered about 30 years ago, has been studied extensively with many X-ray experiments, in particular with the satel­ lites HEAO I and II (see ego Boldt 1987) and with ROSAT (e. g. Hasinger et aI. , 1993). Figure 1 shows a compilation of some of the most recent spectral measure­ ments for the X-ray background. Over the energy range from 3 to about 100 keY its spectrum can be well approximated by an optically thin thermal bremsstrahlung model with kT ~ 40 keY, while at lower X-ray energies a steepening into a new component has been observed observed (e. g.

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.

When I became President of International Astronomical Union Commission 44 for the triennial period 1985-1988, several members of the Organizing Committee and I agreed that it would be a good idea for our Commission to host a conference on observatories in space in view of their increasingly important role in astronomi cal research. IAU Colloquium Number 123 "Observatories in Earth Orbit and Beyond" is the first colloquium sponsored by IAU Com mission 44 on Astronomy from Space, although Commission 44 has co-sponsored numerous colloquia and symposia in the past. The past two decades have seen a flourishing of astronomical observatories in space. Over a dozen orbiting observatories have opened up a new window on the universe, providing hitherto una vailable data in the electromagnetic spectral range from gamma-ray, X-ray, ultraviolet to infrared and radio. This has clearly demon­ strated the crucial nature of astronomical observations from space. The invited talks of present colloquium consist primarily of reviews of currently operating observatories in space, future observatories that have been approved by sponsoring government or space agencies, the launch systems of U.S.A., E.S.A., U.S.S.R. and Japan, discussions of various orbits and sites (such as the Moon), and alternate approaches in designing space observatories. Several panel discus­ sions addressed those issues as well as the major unsolved problems of astronomy. Contributed poster papers included descriptions of space observatories that are in planning stage.

This book was conceived to commemorate the continuing success of the guest observer program for the International Ultraviolet Explorer (IUE) satellite observatory. It is also hoped that this volume will serve as a useful tutorial for those pursuing research in related fields with future space observatories. As the IUE has been the product of the three-way collaboration between the U.S. National Aeronautics and Space Administration (NASA), European Space Agency (ESA) and the British Engineering and Research Council (SERC), so is this book the fruit of the collaboration of the American and European participants in the IUE. As such, it is a testimony to timely international cooperation and sharing of resources that open up new possibilities. The IUE spacecraft was launched on the 26th of January in 1978 into a geosynchronous orbit over the Atlantic Ocean. The scientific operations of the IUE are performed for 16 hours a day from Goddard Space Flight Center in Greenbelt, Maryland, U.S.A, and for 8 hours a day from ESA Villafranca Satellite Tracking Station near Madrid, Spain.