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.

Proceedings of the 69th Colloquium of the International Astronomical Union held in Bamberg, F.R.G., August 31-September 3, 1981

Inhalt
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.