Wide Components in Double and Multiple Stars: Proceedings of the 97th Colloquium of the International Astronomical Union held in Brussels, Belgium, 8–13 June, 1987

Opening Session.- Welcome Address of the Director of the Royal Observatory Belgium.- General Introductory Lecture.- First Session Cataloguing Wide Pairs.- The Concept of Star Multiplicity and its Historical Evolution.- Wide Double Stars with Common Proper Motion.- Wide Pairs in the Washington Double Star Catalogue (WDS).- The Contribution of the Hipparcos Mission and of the CCDM Catalogue to the Study of Wide Systems.- A Photometric Catalogue of Visual and Multiple Stellar Systems.- A General Catalogue of Ephemerides and Apparent Orbits for Visual Binaries.- Second Session Wide Nearby Binaries.- The Third Catalogue of Nearby Stars with Special Emphasis on Wide Binaries.- The Search for Wide Pairs Among Nearby Stars.- A Plea for Better Astrophysical and Astrometric Data in Case of Double Stars of Peculiar Interest.- Third Session Wide Components In Multiple Systems.- Distant Companions in Double and Multiple Stars.- Trapezium-Type Wide Systems.- The Kinematics of Trapezium-Type Systems.- A Survey of the Third Components in Spectroscopic and Eclipsing Systems.- Imaging Approach to Multiple Star Recognition: The Algorithm, the Results.- Physical Parameters of the Massive Multiple System Eta Orionis.- A Search and Classification of Multiple Systems in the General Field.- Fourth Session Observations Of Wide Pairs And Their Results.- Visual Binary Separations as Functions of Primary Types, Ages and Locations.- Photoelectric Observations of CPM Stars in the BVRI System.- On the Wide Binaries in Selected Area 57.- Studies of a Sample of CPM Stars.- Wide Binaries and Old Disk Population Groups.- Orbit Determination from a Short Arc Through the Coefficients of Power Series in Time.- Astrometric Parameters of Visual Double Stars Derived from Simulated Hipparcos Measurements.- Poster Session.- Tentative Comments about the Meeting.- The Space Arrangement of the Orbital Planes of the Visual Double Stars.- A Possible Connection between Wide Binaries and Open Clusters.- New Orbits of Four Visual Double Stars by the Method of Apparent Motion Parameters (AMP).- Are Double Star Observations The Most Suspicious Ones in the Paris Astrolabe Programme?.- Visual Double Stars in Professional Spanish Astronomy: Past, present and Future Projects.- A Method for Calculating the Orbits of Interferometer/Spectroscopic Binaries from Combined data.- The Frequency of Wide Binaries Among the Southern Barium Stars.- Observation et Résolution du Système Triple ? Virginis par la Méthode des Occultations.- The Researches at Torino on Wide Double Stars.- Precise Radial Velocity Measurements of Visual Binary Stars.- Mesures Photographiques d’Étoiles Doubles Visuelles Larges.- Positions Précises d’Étoiles Doubles Visuelles Larges.- Software for Calculating Orbit and Mass of Visual Binaries.- VRI Photometry of Late Dwarf Common Proper Motion Stars.- CCD Suitable for Double Star Astrometry.- Infrared Companions to Pre-main Sequence Stars.- Dynamical Evolution of Triple Systems (Scientific Film).- Fifth Session Statistical Studies On Wide Pairs.- Statistical Studies on Wide Pairs.- Statistical Study of Visual Binaries.- The Optical Fraction of a Hipparcos Sample of Wide Binaries.- Wide Binaries in a Hipparcos Sample Centered Around b = 0°, 1° = 300°.- Sixth Session Origin And Evolution Of Wide Pairs.- Theoretical Models for Wide Binary Evolution.- What Can We Learn from Studies of Wide Binary Statistics.- Evidence of Mass Loss in Visual Binary Stars.- Concluding Remarks.