Planetary Nebulae: (34 International Astronomical Union Symposia)

This written account of the Symposium on Planetary Nebulae was prepared from manuscripts submitted by the participants. Nearly every paper that was presented at the meeting is reproduced here, in either complete or abbreviated form. The dis­ cussions have been somewhat shortened and rearranged, but we have tried to preserve the essential points and the general tenor of the exchanges. Participants who spoke in the discussion were asked immediately for written remarks, which were then edited, reproduced, and circulated at the meeting by the highly effective local Secretariat organized by Dr Perek. In addition, notes of the discussion taken by Mrs Edith F. Swan and by the undersigned were used. We wish to thank all the authors for their unusually good cooperation. We are especially grateful to Dr Minkowski, who kindly provided many excellent repro­ ductions of Mount Wilson and Palomar photographs, mostly taken by himself, of various planetary nebulae. We are particularly indebted to Mrs Swan, who attended the Symposium, made notes on the papers and discussions as they occurred, and did much of the checking and editing of the manuscripts. In addition, we are very grateful to Mrs Evelyn Seaver, who also did much of the checking, editing, and retyping of manuscripts, and to Dr B.L. Webster, Miss Rebecca Todd, Mr Joseph Tapscott, and Mr Dennis Schatz, who provided excellent assistance in the preparation of this volume.

Table of Contents:
An Introductory Review.- Session I — Basic Data.- Planetary Nebulae as a Part of the Galaxy.- Planetary Nebulae in the Magellanic Clouds.- Spectroscopic Observations of Planetary Nebulae in the Magellanic Clouds.- A Preliminary Report of a Survey of Planetary Nebulae in the Southern Hemisphere.- Observed Angular Motions in Planetary Nebulae.- The Space Distribution of Planetary Nebulae.- General Discussion.- Session II — Observations.- The Absolute Spectrophotometry of 170 Planetary Nebulae.- A Photoelectric Photometer for Extended Sources.- Observations of Planetary-Nebula Spectra in the Near Ultraviolet.- Observation des Nébuleuses Planétaires dans l’Infrarouge.- Spectres de NGC 1976, IC 4997, NGC 6572 et IC 418 dans le Proche Infrarouge Photographique.- The Helium ? 10 830 Line in Planetary Nebulae and the Orion Nebula.- Infrared Observations of the Planetary Nebula NGC 7027.- The Ultraviolet Emission Spectra of Planetary Nebulae.- Observations of Planetary Nebulae at Radio Wavelengths.- Radio Emission from Fourteen Planetary Nebulae at 408 MHz.- Radio Observations of Planetary Nebulae.- High-Resolution Radio Observations of Five Planetary Nebulae.- Radio Measurements of Planetary Nebulae.- General Discussion.- Session III — Physical Processes.- Review of Atomic Collision Processes.- Collision Strengths for Excitation of Forbidden Lines.- Transition Probabilities for Forbidden Lines.- Population de Niveaux Fortement Excités.- The Determination of Electron Densities, Electron Temperatures and Central-Star Temperatures for a Series of Planetary Nebulae.- On the Methods of Correction for the Interstellar Reddening of Planetary Nebulae.- On the Determination of Physical Conditions in the Nebulae.- Radiative Transfer Processes in Planetary Nebulae.- Ly-?Radiation Densities in Planetary Nebulae.- The Ionization of Planetary Nebulae.- The Ionisation Equilibrium for Heavy Elements.- The Chemical Composition of Planetary Nebulae.- General Discussion.- Session IV — Structure and Dynamics.- Morphological Study of Planetary Nebulae.- Problems of Gas Dynamics in Planetary Nebulae.- Sur la Structure Morphologique et Cinématique de la Nébuleuse ‘Helix’.- Filaments of the Helix Nebula.- Internal Motions in the Planetary Nebula NGC 6543.- Emission-Line Profiles in Planetary Nebulae.- Internal Motions in the Planetary Nebula NGC 6853.- Dynamical Evolution of a Model Planetary Nebula.- Explanation of Different Shapes of Planetaries in Terms of Movement in Magnetic and Gravitational Fields.- The Role of Magnetic Fields in the Origin and Structure of Planetary Nebulae.- The Observation of Monochromatic Intensity Distributions in Planetary Nebulae by Means of Electronography.- On the Orientation of the Major Axes of Planetary Nebulae.- General Discussion.- Session V — Central Stars.- The Atmospheres and Spectra of Central Stars.- UBV Photometry of the Bright Nuclei of the Planetary Nebulae.- Photometric Observations of the Central Stars of Planetary Nebulae.- The Binary-Star Hypothesis for the Nucleus of NGC 1514.- Radial Velocity of the Central Star of NGC 1514.- A Method of Determination of the Temperature of Nuclei of the Planetary Nebulae.- The Possibility of Beta decay in the Atmospheres of Nuclei of Planetary Nebulae.- Spectra of the Central Stars of Planetary Nebulae.- General Discussion.- Session VI — Origin and Evolution.- Observational Aspects of the Evolution of Planetary Nebulae and their Central Stars.- Probable Variability of NGC 6572.- On the Variability of the Nuclei of Three Planetary Nebulae.- On theVariability of the Central Star of the Planetary Nebula HZ 1–5.- Long-Period Variables and Planetary Nebulae.- Pulsational Instability and the Origin of Planetary Nebulae.- Dynamical Instability of the Envelopes of Red Supergiants and the Origin of Planetary Nebulae.- Production of Planetary Nebulae.- On the Question of the Origin of Planetary Nebulae.- Evolution of Central Stars of Planetary Nebulae Theory.- Evolution towards the White-Dwarf Stage.- Chemical Composition and Distribution of White Dwarfs.- Implications of White-Dwarf Crystallization for the Chemical Composition of the Planetary Nuclei.- On the Evolution of the Central Stars.- The Evolution of Helium Shell-Burning Stars.- General Discussion.- Session VII — Concluding Discussion.- Physical Processes.- Galactic Dynamics and Galactic Distribution.- Radio Emission.- Kinematics and Dynamics.- Structure.- Origin and Evolution.- General Discussion.