Proceedings of IAU Symposium No. 75 held in Geneva, Switzerland, September 6-10, 1976. Dedicated to Solomon Pikel'ner

Symposium No. 73 of the International Astronomical Union was devoted to the obser vational and theoretical aspects of close binary stars. Just over 100 participants attended. The Local Organizing Committee would like to thank the following: IAU for travel grants. IBM United Kingdom Ltd for very generous support in the form of travel grants. The Royal Society for the provision of travel grants to participants from Eastern Europe. We also thank the Director of the Institute of Astronomy, and our colleagues and research students for their moral support and assistance. Finally we thank Pauline Haughey for assisting with the editorial work. PETER EGGLETON SIMON MITTON JOHN WHELAN SCIENTIFIC ORGANIZING COMMITTEE M. Plavec (Chairman), T. Herczeg, E. P. J. van den Heuvel, J. B. Hutchings, G. Larsson-Leander, L. B. Lucy, L. Mestel, B. Paczynski, J. Sahade, B. Warner, R. E. Wilson. LOCAL ORGANIZING COMMITTEE J. A. J. Whelan (Chairman), P. P. Eggleton, S. A. Mitton LIST OF PARTICIPANTS Baldwin, B. W., Victoria, Canada Icke, V., Cambridge, England Bateson, F. M., Tauranga, New Zealand Koumsiachvilli, M., Moscow, U.S.S.R Bath, G. T., Oxford, England Krzeminski, W. A., Warsaw, Poland Batten, A. H., Victoria, Canada Larsson-Leander, G., Lund, Sweden Berthier, E. J., Paris, France Leung, K.-C., Nebraska, U.S.A."

The International Astronomical Union Symposium No. 70 on Be and Shell Stars, the Merrill-McLaughlin Memorial Symposium, was held in Bass River (Cap Cod), Massachusetts, U. S. A. , from September 15th through 18th, 1975. Fifty-three astronomers from Argentina, Belgium, Canada, Czechoslovakia, France, Israel, the United Kingdom, the United States, and the Vatican attended and participated in the Symposium. This volume, which parallels the actual program closely, contains the papers presented at the Symposium plus most of the discussion following the papers. New observational techniques and fresh theoretical ideas have resulted over the past few years in a renewed interest in Be and shell stars. At IAU Symposium No. 51 on Extended Atmospheres and Circumstellar Matter in Spectroscopic Binary Sys tems, the Otto Struve Memorial Symposium, in Parksville, British Columbia, Canada, three years ago, a number of participants expressed the wish to organize a symposium on Be and shell stars. If we wish to identify an official 'Father of IAU Symposium No. 70', it would be Mirek Plavec who, in his capacity as President of IAU Commission 42 (Photometric Double Stars) requested and received the cooperation of Commissions 29 (Stellar Spectra) and 36 (Stellar Atmospheres), suggested an Organizing Committee, and wrote to the IAU General Secretary in 1973 requesting that the IAU Executive Committee approve the proposed confer ence as an IAU Symposium.

The general discussions of the roles of photometric and spectroscopic classification at Cordoba in 1971 (lAU Symposium No. 50), and of the calibration of classification indices at Geneva in 1972 (IAU Symposium No. 54), revealed clearly the steadily in creasing importance of abundance parameters. The multipliCity of these, however, raised so many new problems that it was logical that the 1975 meeting at Lausanne should be concerned with ways in which differences in abundance affect both spectral types and photometric indices. Commissions 29 and 36 joined with Commission 45 in sponsoring this Symposium. Since the date of the meeting came shortly after the formal retirement of Professor William W. Morgan from the University of Chicago, it was quickly agreed that this meeting should be dedicated to him in recognition of his unique contributions to spectral classification. In the opening paper of the Symposium Dr. Bengt Stromgren has summarized these. To his remarks we should add only that it was about 1940 that Morgan first distinguished the group of G- and K-type stars with weak CN bands and metallic lines - stars which have since been recognized as having the abundance of all metals relative to hydrogen much lower than in stars of the solar population. Spectra of two of these, HD 81192 (Boss 2527) and 8 Lep, were later shown as examples of the group in the Yerkes Atlas of 1943."

The idea of holding this Symposium has its origin in a conversation with G. Con to poulos during the winter of 1973. It was then clear that the progress realized in Stellar Dynamics since the Thessaloniki symposium had given a new shape to the field. Other meetings such as the C. N. R. S. colloquium held in Paris in 1967 or the LA. V. colloquium held in Cambridge, England, in 1970 had in the meantime given opportunities to review the advances achieved in several branches of this field. We thought that time had come to organize a general confrontation of the new results obtained in the approach of the gravitational N-body problem by different methods, in the investigation of spherical and flattened systems, in the comparisons with ob servations and in more theoretical speculations on orbits, integrals of motion, dense nuclei or relativistic stellar dynamics. Things were made easy by the support of Commissions 33 and 37 which welcomed the proposition and by 1. R. King who accepted to act as Chairman of the Scientific Organizing Committee. The final decision to meet in Besan'Yon was taken during the XVth General Assembly of the LA. U. in Sydney in August 1973. The members of the Organizing Committee were: 1. R. King (Chairman), G. Con topoulos, A. Hayli, M. Henon, G. Hori, D. Lynden-Bell, L. Perek, L. Spitzer, R. Wielen, Ya. Zel'dovich while the members of the Local Committee were: A."

This book contains a set of articles based on a session of the annual meeting of the American Association for the Advancement of Science held in San Francisco in February, 1974. The reason for the meeting arose from the need to communicate to the largest possible scientific community the dramatic advances which have been made in recent years in the understanding of collapsed objects: neutron stars and black holes. Thanks to an unprecedented resonance between X-ray, y-ray, radio and optical astronomy and important new theoretical developments in relativistic astro physics, a new deep understanding has been acquired of the physical processes oc curring in the late stages of evolution of stars. This knowledge may be one of the greatest conquests of man's understanding of nature in this century. This book aims to give an essential and up-to-date view in this field. The analysis of the physics and astrophysics of neutron stars and black holes is here attacked from both theoretical and experimental points of view. In the experimental field we range from the reviews and catalogues of galactic X-ray sources (R. Gursky and E. Schreier) and pulsars (E. Groth) to the observations of the optical counter part of X-ray sources (P. Boynton) to finally the recently discovered gamma-ray bursts (I. Strong) and pulse astronomy R. B. Partridge)."

Colloquia and symposia have almost become a tradition among the variable-star astronomers; those held more or less regularly at Bamberg and Budapest have become well known. For a change, this time the organizing committee of Commission 27 decided to hold an LA. U. symposium in Moscow and to adopt as a special topic the relation between variable stars and the evolution of stars and stellar systems. This symposium, No. 67 in the LA. U. series, was prepared by two committees, a by B. V. Kukarkin, and a local one with V. A. Ambartsumian scientific one chaired as chairman, and G. S. Khromov as executive secretary. It was held in Moscow at the Physical and Astronomical Institutes of the Lomonosov University from July 29 to August 4, 1974. The symposium was opened with three short welcoming speeches by V. A. Ambartsu mian, J. M. Ternov (vice-rector of Moscow University), and B. V. Kukarkin. All three stressed the importance of the study of variable stars in connection with the evolution of stars and stellar systems, the role of the Russian astronomers in these studies, and the necessity of international cooperation."

Pulsars, generally accepted to be rotating neutron stars, are dense, neutron-packed remnants of massive stars that blew apart in supernova explosions. They are typically about 10 kilometers across and spin rapidly, often making several hundred rotations per second. Depending on star mass, gravity compresses the matter in the cores of pulsars up to more than ten times the density of ordinary atomic nuclei, thus providing a high-pressure environment in which numerous particle processes, from hyperon population to quark deconfinement to the formation of Boson condensates, may compete with each other. There are theoretical suggestions of even more "exotic" processes inside pulsars, such as the formation of absolutely stable strange quark matter, a configuration of matter even more stable than the most stable atomic nucleus, T56Fe. In the latter event, pulsars would be largely composed of pure quark matter, eventually enveloped in nuclear crust matter. These features combined with the tremendous recent progress in observational radio and x-ray astronomy make pulsars nearly ideal probes for a wide range of physical studies, complementing the quest of the behavior of superdense matter in terrestrial collider experiments. Written by an eminent author, Pulsars as Astrophysical Laboratories for Nuclear and Particle Physics gives a reliable account of the present status of such research, which naturally is to be performed at the interface between nuclear physics, particle physics, and Einstein's theory of relativity.

The XXth meeting of the IAU in Australia in 1973 made the venue for the IAU Symposium No. 59 on Stellar Instability and Evolution, at Mount Stromlo Obser vatory on August 16-18, a very appropriate one. Many of the current and former staff of Mount Stromlo Observatory (operated by the Australian National Univer sity) have specialized in the study of variable stars and it was with considerable pleasure that Mount Stromlo Observatory accepted the responsibility of hosting and making the local arrangements for IAU Symposium No. 59. The Scientific Organizing Committee was particularly active in formulating the program and comprised Drs N. Baker, P. Demarque, M. Feast, G. Herbig, I. Iben, P. Ledoux, J. Ostriker and E. Schatzman. The aim of the Committee was to integrate the review and contributed papers on the particular instability mechanisms involved, their observational manifestations and their relation to the internal structure of the star as inferred from its evolutionary history. The Local Organizing Committee consisted of Miss P. Petrie and A. W. Rodgers."

'Galactic Radio Astronomy' was chosen as the subject of this Symposium, which was held in conjunction with the IAU General Assembly that took place in Sydney in August 1973, largely because it is a very suitable Southern Hemisphere topic. This results in part from the advantages of a southern location in studying the Galaxy and in part from the long association of Australia with radio astronomy. Following the General Assembly, the Symposium was held at the Surf air Inter national Hotel in Maroochydore, Queensland, from 3 to 7 September, 1973. The conference participants were effectively isolated from the rest of the world during the Symposium, and the excellent spring weather and geographical situation led to the development of an unusually good rapport. The Symposium was sponsored by Commissions 40, 33, and 34. The Organizing Committee was composed of A. H. Barrett (chairman), J. E. Baldwin, D. S. Heeschen, F. J. Kerr, J. Lequeux, S. W. McCuskey, P. G. Mezger, B. Y. Mills, Yu. N. Parijskij, B. J. Robinson, H. van der Laan, and H. F. Weaver. The Local Committee, consisting ofB. J. Robinson, N. G. Seddon, and P. J. Kelly, looked after the arrangements in very fine style. The Symposium was supported financially by the IAU, the Australian Academy o Science, the CSIRO Division of Radiophysics, Union Carbide Australia Limited, and the Science Foundation for Physics within the University of Sydney."

Proceedings of IAU Symposium No. 58 held in Canberra, Australia, August 12-15, 1973

Proceedings of IAU Symposium No. 53 held in Boulder, Colorado, 21-26 August 1972

In connection with arranging IAU Symposium No. 50 on 'Spectral Classification and Multicolour Photometry', sponsored by Commissions 45 and 25, it was decided to exclude all calibration problems. Instead it was agreed that we should attempt to arrange a separate symposium, dealing with the fundamental problems of the cali bration of absolute magnitudes and temperatures of stars. The Executive Committee of the IAU accepted our proposal, and IAU Symposium No. 54 was held in Geneva on September 12-15, 1972, sponsored by thefollowing IAU Commissions: 24, 25, 29, 33, 35, 37,44 and 45. It was attended by about 90 scientists representing 16 countries. The Symposium was divided into eight sessions. Each session started with a review paper by an invited speaker; this was followed by a general discussion including a few contributed papers. The contents of the present volume follow closely the programmes of the individual sessions of the Symposium. Most of the recorded discussions have been kept, and only in a few cases have the order of questions and comments been altered so as to obtain more homogeneity in the presentation."

The proposal to organize a Symposium on circumstellar matter and extended atmo spheres in binary systems was first made by the Dominion Astrophysical Observatory to the Executive Committee of the International Astronomical Union in the summer of 1969. It received the support of the presidents of Commissions 29 (Stellar Spectra), 30 (Radial Velocities), 36 (Stellar Atmospheres), and 42 (Photometric Double Stars). Approval in principle was given by the Executive Committee almost immediately, and the Committee further suggested that the Symposium be officially designated the Struve Memorial Symposium. Final approval was given at the time of the 1970 General Assembly of the Union. when the dates of the Symposium were set for August or September, 1972. The Organizing Committee set up consisted of K. O. Wright (Chairman), A. H. Batten, K. -H. B6hm, A. A. Boyarchuk, G. Larsson-Leander, and M. Plavec. In addition, J. Sahade and F. B. Wood acted as advisory members. Local organization was entrusted to a committee consisting of A. H. Batten, E. K. Lee, and C. D. Scarfe. The final dates selected were September 6-12, 1972, and the Sym posium was held at the Island Hall Hotel, Parksville, B. C., on Vancouver Island some 90 miles from Victoria. The Organizing Committee attempted to arrange a Symposium of the type in which no contributed papers would be presented and discussion would range as widely as possible over the field covered by the six invited review papers."

We have in this volume, compiled a connected account of the proceedings of the Symposium on Wolf-Rayet and High-Temperature Stars held at Buenos Aires. The Organizing Committee had assigned broad areas of topical interest to be reviewed by invited speakers. Each of these presentations was followed by lengthy discussions that were tape recorded and transcribed later. These discussions have been edited only to a limited extent. We have shortened them and rearranged them to bring about a greater coherence. We have, however, attempted to retain the tenor of the discussions, the flavour of impromptu remarks and the continuity of an argument. Much of the success of such a venture depends on the contributors to the discussions. To be able to make these thoughts available to a larger audience has been the task of those re sponsible for the elaborate tape recording of the proceedings. We thank those at the Instituto de Astronomia y Fisica del Espacio for the efficient way in which this re sponsibility has been discharged. Many at Buenos Aires and Kodaikanal have contrib uted efficient assistance to the preparation of this volume and we are deeply indebted for their help. In particular, two amongst these, Nora Martinez and A. M. Batcha have contributed overwhelmingly both to the organization of the symposium and the final preparation of the symposium volume. Financial support for this symposium came from the International Astronomical Union and the Argentine National Research Council."

The classic account of the structure and evolution of the early universe from Nobel Prize-winning physicist P. J. E. Peebles An instant landmark on its publication, The Large-Scale Structure of the Universe remains the essential introduction to this vital area of research. Written by one of the world's most esteemed theoretical cosmologists, it provides an invaluable historical introduction to the subject, and an enduring overview of key methods, statistical measures, and techniques for dealing with cosmic evolution. With characteristic clarity and insight, P. J. E. Peebles focuses on the largest known structures-galaxy clusters-weighing the empirical evidence of the nature of clustering and the theories of how it evolves in an expanding universe. A must-have reference for students and researchers alike, this edition of The Large-Scale Structure of the Universe introduces a new generation of readers to a classic text in modern cosmology.

Based on the very popular liberal arts course Bob Bless has taught at University of Wisconsin for many years, this book provides a rich, historical approach to introductory astronomy. It is ideal for use in an introductory astronomy course for nonmajors. In the fifteen years since the first edition of this text was published, several new concepts such as dark matter, dark energy, and an incredible expansion of the universe (inflation) have been developed. Furthermore, many of the exotic effects predicted by General Relativity (e.g. black holes, warped space) have gone from being interesting theoretical speculations to useful practical tools for understanding the universe. This book aims to give an overview of astronomy, but in such a way that the non-science major can get a feeling for how science actually developed with its false starts and wrong turns, which observational evidence eventually corrected, and also to describe the incredible recent developments in our understanding of the physical universe. Several chapters of this 2nd edition have been extensively revised to include these recent developments. Because it has become increasingly difficult to "cover" all of astronomy in a one-semester course, this edition has largely omitted coverage of the physical nature of the objects in our, and other, planetary systems, although a discussion of the possibility of life elsewhere closes the book.

From supernovae and gamma-ray bursts to the accelerating Universe, this is an exploration of the intellectual threads that lead to some of the most exciting ideas in modern astrophysics and cosmology. This fully updated second edition incorporates new material on binary stars, black holes, gamma-ray bursts, worm-holes, quantum gravity and string theory. It covers the origins of stars and their evolution, the mechanisms responsible for supernovae, and their progeny, neutron stars and black holes. It examines the theoretical ideas behind black holes and their manifestation in observational astronomy and presents neutron stars in all their variety known today. This book also covers the physics of the twentieth century, discussing quantum theory and Einstein's gravity, how these two theories collide, and the prospects for their reconciliation in the twenty-first century. This will be essential reading for undergraduate students in astronomy and astrophysics, and an excellent, accessible introduction for a wider audience.

Illustrated with breathtaking images of the Solar System and of the Universe around it, this book explores how the discoveries within the Solar System and of exoplanets far beyond it come together to help us understand the habitability of Earth, and how these findings guide the search for exoplanets that could support life. The author highlights how, within two decades of the discovery of the first planets outside the Solar System in the 1990s, scientists concluded that planets are so common that most stars are orbited by them. The lives of exoplanets and their stars, as of our Solar System and its Sun, are inextricably interwoven. Stars are the seeds around which planets form, and they provide light and warmth for as long as they shine. At the end of their lives, stars expel massive amounts of newly forged elements into deep space, and that ejected material is incorporated into subsequent generations of planets. How do we learn about these distant worlds? What does the exploration of other planets tell us about Earth? Can we find out what the distant future may have in store for us? What do we know about exoworlds and starbirth, and where do migrating hot Jupiters, polluted white dwarfs, and free-roaming nomad planets fit in? And what does all that have to do with the habitability of Earth, the possibility of finding extraterrestrial life, and the operation of the globe-spanning network of the sciences?

The study of AGN is one of the most dynamic areas of contemporary astronomy, involving one-fifth of all research astronomers. This textbook provides a systematic review of the observed properties of AGN across the entire electromagnetic spectrum, examines the underlying physics, and shows how the brightest AGN--quasars--can be used to probe the farthest reaches of the Universe. This timely textbook is a clear, comprehensive and self-contained introduction to active galactic nuclei (AGN)--for advanced undergraduates and graduate students in astronomy and physics.

'fascinating' Brian Cox This is the story of citizen science. Where once astronomers sat at the controls of giant telescopes in remote locations, praying for clear skies, now they have no need to budge from their desks, as data arrives in their inbox. And what they receive is overwhelming; projects now being built provide more data in a few nights than in the whole of humanity's history of observing the Universe. It's not just astronomy either-dealing with this deluge of data is the major challenge for scientists at CERN, and for biologists who use automated cameras to spy on animals in their natural habitats. Artificial intelligence is one part of the solution-but will it spell the end of human involvement in scientific discovery? No, argues Chris Lintott. We humans still have unique capabilities to bring to bear-our curiosity, our capacity for wonder, and, most importantly, our capacity for surprise. It seems that humans and computers working together do better than computers can on their own. But with so much scientific data, you need a lot of scientists-a crowd, in fact. Lintott found such a crowd in the Zooniverse, the web-based project that allows hundreds of thousands of enthusiastic volunteers to contribute to science. In this book, Lintott describes the exciting discoveries that people all over the world have made, from galaxies to pulsars, exoplanets to moons, and from penguin behaviour to old ship's logs. This approach builds on a long history of so-called 'citizen science', given new power by fast internet and distributed data. Discovery is no longer the remit only of scientists in specialist labs or academics in ivory towers. It's something we can all take part in. As Lintott shows, it's a wonderful way to engage with science, yielding new insights daily. You, too, can help explore the Universe in your lunch hour.

From time immemorial, poets and philosophers have looked in awe and wonder at the Universe. Such awe is shared by astrophysicists, too, as they seek to understand its nature, and whether it has any limits. In The Infinite Cosmos, Joseph Silk, Savilian Professor of Astronomy at Oxford University, cosmologist and well-known science writer, brings together the modern understanding of the Universe, its structure, its evolution, and its possible fate, combining the latest from theory and observation. The narrative is peppered with quotations from literature and philosophy, and reflects, too, on the process of scientific discovery, and the implications of our discoveries.

In this book, the authors present current research in galactic study including its evolution, morphology and dynamics. Topics included in this compilation include the nature of motion in quiet and active galaxies with a satellite companion; empirical age-metallicity relation and empirical metallicity distribution of long-lived stars of different populations; radio quiet AGN properties vs. spin paradigm; and turbulent formation of protogalaxies at the end of the plasma epoch.

Ongoing studies in mathematical depth, and inferences from helioseismological' observations of the internal solar rotation have shown up the limitations in our knowledge of the solar interior and of our understanding of the solar dynamo, manifested in particular by the sunspot cycle, the Maunder minimum, and solar flares. This second edition retains the identical overall structure as the first edition, but is designed so as to be self-contained with the early chapters presenting the basic physics and mathematics underlying cosmical magnetohydrodynamics, followed by studies of the specific applications appropriate for a book devoted to a central area in astrophysics.
New to this edition:
Chapter 6 gives an account of the present state of dynamo theory in general, and Chapter 8 the applications to the Sun and to other Late-Type' stars with differing rotation rates -- the Solar-Stellar Connection'. The minority of the more massive Early-Type' stars that are observably magnetic are well described by theoblique rotator' model, with a quasi-steady, fossil' magnetic structure frozen' into the highly conducting, non-turbulent envelope. Chapter 9 deals with the considerable progress on the associated theoretical problems.
Chapter 7 contains new material, relevant to both Late- and Early-Type Main Sequence stars, to the evolved Red Giants, and also to contracting pre-Main Sequence stars (Chapter 10}, which show the highest degree of magnetic activity (the magneto-rotational instability, and the magneto-centrifugal winds emitted by the surrounding accretion disk'). In the earlier phases of star formation in molecular clouds (Chapters 11-12), magneto-turbulence' is emerging as the appropriate scenario for the prediction of the mass spectrum of proto-stars, and the associated formation of planetary satellites. Chapter 14 describes developments in the study of the magnetosphere of a pulsar' -- a magnetized neutron star -- consisting of spontaneously generated electron-positron pairs.

Pulsars are highly magnetised, rotating neutron stars that emit a beam of electromagnetic radiation. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name. This book reviews research from around the globe in the field of pulsars including anomalous X-ray pulsars; the arrival directions of ultrahigh energy extensive air particles registered at the Yakutsk extensive air shower array from 1974 to 2007; the observed rotation period of pulsar time properties; measuring the moment of inertia of the double pulsar and its usefulness in testing modified models of gravity and others.