Binary and Multiple Stars as Tracers of Stellar Evolution: Proceedings of the 69th Colloquium of the International Astronomical Union, Held in Bamberg, F.R.G., August 31 - September 3, 1981

If Zdenek Kopal Department of Astronomy University of Manchester Your Magnificences, my Lord Mayor, ladies and gentlemen! It is a great pleasure for me to respond, on behalf of your foreign guests, to your gracious words of welcome; and to thank you for the wonderful reception which you nave extended to us. The city of Bamberg and its Remeis Sternwarte nas indeed been renowned allover the world for a great many years - as the place where your Observatory's first director, Professor Ernst Hartwig (1851-1923) - in addition to his other titles to fame - collaborated (with Gustav Muller of Potsdam) on the construc­ tion of the monumental Geschichte und Literatur des Lirhtwechsels der Veranderlichen Sterne, which since 1918 has (together with its sub­ sequent continuation) been a veritable vade-mecum of a1l students of variable stars; where the second director, Professor Ernst Zinner (1886-19]~ prepared his valuable Katalog der Verdachtigen Veranderlichen Sterne (192@ which safeguarded many an astronomer (including the present speaker in the days of his innocence) from premature discovery claims; and whose third director, Professor Wolfgang Strohmeier, initiated in 1959 the tradition of the international colloquia of which ours is the latest successor. It is indeed a great pleasure to welcome Professor Strohmeier - now Emeritus - among us; and to congratulate him on the grace with which he is carrying his years.

I Evolution of Stars in the Post-Main Sequence Stage.- Evolution of Stars in the Post-Main Sequence Stage.- Disk Instabilities in Hubble-Sandage Variables?.- The Frequency of Cepheid Binaries.- Search for Pulsating Stars in Multiple Stellar Systems.- An AD HOC Hypothesis on the Pulsation of Delta Scuti Stars.- On the Internal Structure of Main-Sequence Stars.- A Study of the Orbital Periods of 22 Eclipsing Binaries.- On the Group Formation of Stars in Stellar Associations.- The Age of the Triple System HD 165590.- Properties of Relativistic Linear Stellar Models.- II Evolutionary Trends in Wide Binary Systems.- Evolutionary Trends in Wide Binaries.- A Note about Multiple Systems of Dense Molecular Clouds.- Trapezium Type Multiple Systems and Formation of Stars.- A Hypothesis on the Richness of a Galaxy in Binary Stellar Systems.- A Mass-Eccentricity Correlation in Spectroscopic and Visual Binary Orbits.- Photometric Investigation of Visual Binaries with a Component above the Main Sequence.- On the Distribution of Young Spectroscopic Binary Stars over the Major Semiaxes of their Orbits.- Observational Selection in Spectroscopic Binary Eccentricities.- Double Stars: The Closest and the Most Distant Systems.- The Evolutionary State of Zeta Aurigae.- III Evolutionary Processes in Close Binary Systems.- Evolution of Close Binary Stars: Observational Aspects.- Statistical Properties of Algol-Type Systems.- Mass Loss in Algol-Type Stars: Implication on their Evolutionary Stage.- Ultraviolet Light Curves of U Geminorum and VW Hydri.- Statistical Models for Close Binaries.- Structure and Evolution of SV Centauri.- Age Determination in CW ERI = BV 1000.- Numerical Calculations for Accretion Disks in Close Binary Systems.- Quasi-Simultaneous Photometric and Polarimetric Observations of T TAU and RY TAU.- S CNC as a Case Study of Classical Algol Evolution.- Structural Models for Beta Lyrae-Type Disks.- Evolutionary Effects in Contact Binaries.- Evolutionary Possibilities and Impossibilities for Solar Type Contact Binaries in NGC 188.- Origin and Evolution of Contact Binaries of W UMA Type.- Some aspects of the Evolutionary Status of W Ursae Majoris Binaries Deduced from Observational Data.- A Possible Explanation of Distortions in the Light Curves of VW CEP by Starspots.- The IUE Observations of W UMA.- Mass Flow due to Heating in a Binary System: Application to U Cephei.- The Very Unusual Ultraviolet Spectra of R Arae.- On a Possible Linkage between W-Type W UMA Systems and the Short Period Rscvn-Like Binaries.- Recent Observational Evidence on W Ursae Majoris Stars.- The Time Change of the AW UMA System.- The Short-Period Non-Contact Binary Systems UU Lyn and GR TAU.- On the Spatial Density of W UMA Type Stars.- IV Cataclysmic Binaries and their Role in Stellar Evolution.- Binary Stars and SS433.- Observations of Secular Changes in the Kinematic Model of SS433.- Time Resolved Circular Polarimetry of White Dwarf Pulsars.- The Mass Distribution of White Dwarfs and Central Stars of Planetary Nebulae.- Abundance Peculiarities in White Dwarf Atmospheres as a Result of Binary Evolution?.- The Minimum Orbital Period of Hydrogen-Rich Cataclysmic Binaries.- Remarks on the Evolutionary Status of Cataclysmic Variables.- Supernovae in Binary Systems: Production of Runaway Stars and Pulsars.- An Optical Burst in SCO X-1.- The Formation of Massive White Dwarfs in Cataclysmic Binaries.- UV Spectroscopy of the Novalike Variable TT Arietis.- The Subdwarf Eclipsing Binary LB3459 (AA DOR).- Variability of Soft X-Ray Emission of Ex Hydrae Observed with Einstein Observatory.- On the Possible Short-Period Irregular Light Fluctuations of V1357 Cyg = Cyg X-1.- PU Vulpeculae (Object Honda-Kuwano 1979) — A Possible Short-Period Relative of the Symbiotic Stars.- DID SU UMA Undergo a Classical Nova Outburst?.- Does the Cataclysmic Binary Z Cha Contain a Black Dwarf Secondary?.- Concluding Remarks.