The ionosphere of the Earth has been actively studied since the 1920's, following the discovery of ground radio-sounding. By means of this method results were ohtained by an international network of ionospheric stations, in particular, by the successful implementation of a number of rigorously planned international scientific research programs, '" enabling the collection of extensive experimental material on some of the most important parameters of the ionosphere - the critical freLjuencies of E-, Fl and F2-layers. Comprehensive analyses of these observation data give a fairly complete picture of the various changes taking place in the principal ionospheric layers at different points on our globe. Another important aspect of the study of the ionosphere, which has been in progress for the past three decades, is an extensive program of in situ determinations of the various physical parameters - first using rockets, and subsequently artificial satellites. The data thus obtained on the principal ionizing agent - short-wave solar radiation - and on the physical conditions prevailing in the upper atmosphere and in the ionosphere at different altitudes, allow the proposal of a self-consistent mechanism of ionosphere formation. A general outline of the theory of ionosphere formation at different altitudes is now complete. Its application to specific cases, dependent on a more accurate determination of input parameters to give solutions valid for a definite set of conditions etc., is yet to be accomplished. The use of artificial satellites in cosmic research yielded abundant scientific data."

There is abundant evidence that essentially all luminous hot-star winds contain time-dependent and anisotropic structures. IAU Colloquium 169 was convened to review the observations of variability and asphericity, to discuss the physical processes that might cause such behavior and to look for evolutionary consequences. The topics included OBA stars, Be stars, Wolf-Rayet stars, Be stars, and luminous blue variables (LBVs). The role played by rotation in shaping the stellar wind was a recurrent theme. Photospheric pulsations and/or magnetic fields are particularly appealing mechanisms for triggering the formation of recurrent wind structures.

This volume summarizes recent developments in our understanding of active galactic nuclei, including quasars, seyfert galaxies and radio galaxies. The predominant emphasis is put on observational results with information from essentially all wave bands, but important theoretical results are also presented. Among the contributions are discussions of the different types of active galaxies, the nature of the central engine, the wiggly structure of radio jets, the dynamics of the gas in jets, the study of millimeter and extreme ultraviolet regions, and a discussion of the observed continuum of the entire electromagnetic spectrum. The intended readers are professional astronomers and astrophysicists as well as graduate students in this field of research.

The proceedings of this workshop should probably be prefaced with a few words on some of the more confusing jargon. The phrases "Very Low-Mass star" , "VLM star", or simply "VLM" are now used fairly uniformly by as tronomers studying the stars at the bottom of the hydrogen-burning stellar main sequence - unfortunately, however, there is no clear definition as to what constitutes a VLM star. The reader should be warned that VLM stars are variously considered to be stars with; masses less than 0.3M ; masses 0 less than 0.1M ; spectra later than about M6-7; luminosities fainter than 0 Mv = 15; or luminosities fainter than Mbol = 12. The important features of a VLM star, however, would seem to be (1) that it is about as faint as a star can be, and (2) that it still remains a star (ie. it still burns hydrogen) . All of the above criteria, therefore, would seem to qualify an object as a VLM star, and requiring a more stringent definition is probably quibbling.

The 14 papers in this collection discuss recent progress in areas such as mixing in stellar interiors, redistribution and loss of angular momentum, emphasizing in particular the effects of turbulence. An introductory review by E. Schatzman, to whom this volume is dedicated, is followed by three sections: observational facts (surface abundances, stellar rotation, loss of mass and angular momentum, etc.), physical knowledge (mass transport and mixing by waves, turbulent transport, fast dynamo action, etc.), and the interpretation of observations.

Large-scale structures in the universe are becoming ever more important in modern astrophysics. This volume is dedicated to the memory of the late astrophysicist Fritz Zwicky and presents 34 lectures dealing with observational and theoretical aspects of the morphology of the universe. Reports on the distribution, properties and evolution of groups, clusters and superclusters of galaxies, as well as theoretical attempts to explain these findings using such ideas as biased galaxy formation and cold dark matter, are presented here for researchers and students of astronomy and astrophysics.

volume XIX A of IAU Transactions contains the reports by Presidents of Commissions, covering the period July 1981 - June 1984. The topics of IAU Commissions deal with all of contemporary astronomy and the present volume therefore constitutes an exhaustive and unique record of astronomical research during this interval. It is particularly useful for astronomers and other scientists who want to gain an overview of a certain field, not necessarily near their own research area. Each Commission President was requested, by early 1984, to begin prep arations for the compilation of his/her Commission report. All members of Commissions were asked to supply details about their individual research pro grammes. The ensuing, very substantial task of concatenating was undertaken in late 1984 by the Presidents, often supported by a team of authors, all recog nized authorities in their fields. In order to preserve some measure of uni formity - which is in any case very difficult with so many authors - editorial guidelines were sent to Presidents, including the number of pages allotted to each Commission.

This publication is a result of three meetings, each 5 days long, held at the Goddard Space Flight Center on January 24-28, 1983, June 8-14, 1983, and February 13-17, 1984. The meetings were held in the interim between the full operations of the Solar Maximum Mission (SMM) in 1980, and the renewed operations after its repair in orbit in April 1984. Their general objectives were as follows: o Synthesize flare studies after three years of SMM data analysis. Many analyses of individual flares and individual phenomena, often jointly across many data sources had been published, but a need existed for a broader synthesis and updating of our understanding of solar flares since the Skylab Flare Workshops held several years earlier. o Encourage a broader participation in the SMM data anlysis and combine this more fully with theory and other data sources--data obtained with other spacecraft such as the HINOTORI, P78-1, and ISEE-3 spacecrafts, and with the Very Large Array (VLA) and many other ground-based instruments. Many coordinated data sets, unprecedented in their breadth of coverage and multiplicity of sources, had been obtained within the structure of the Solar Maximum Year (SMY). o Stimulate joint studies, and publication in the general scientific literature. The intended primary benefit was for informal collaborations to be started or broadened at the Workshops with subsequent publications. o Provide a special publication resulting from this Workshop. o Provide a starting point of understanding for planning renewed full observations with the repaired SMM.

For some time to come, this book should be the main source for research in prominences. It surveys the results of the past years, including the "Hvar Reference Atmosphere", which was developed by a panel as a model for quiescent prominences. The reader will find papers on the formation of and physical conditions in prominences, on magnetic fields, on mass motion and energy flow, and on the prominence-corona interface.

Humans have long thought that planetary systems similar to our own should exist around stars other than the Sun, yet the search for planets outside our Solar System has had a dismal history of discoveries that could not be confirmed. However, this all changed in 1995, after which astonishing progress can be seen in this field; we now know of more than 200 extrasolar planets. These findings mark crucial milestones in the search for extraterrestrial life - arguably one of the most intriguing endeavors of modern science. These proceedings from the 2005 Space Telescope Science Institute Symposium on Extrasolar Planets explore one of the hottest topics in astronomy. Discussions include the Kepler mission, observational constraints on dust disk lifetimes and the implications for planet formation, and gravitational instabilities in protoplanetary disks. With review papers written by world experts in their fields, this is an important resource on extrasolar planets.

The Local Group of galaxies consists of the Milky Way and all of its neighbours. The proximity of these galaxies allows for detailed studies of the processes that have led to their formation, structures, and evolution. In particular, studies of the Local Group can test predictions of structure formation that are based on dark energy and cold dark matter. This book presents a collection of review papers, written by world experts, on some of the most important aspects of Local Group Astrophysics. It is an invaluable resource for both professional researchers and graduate students in this fascinating area of research.

Supernovae are gigantic stellar explosions. The effects of these rare events pervade astronomy, creating and spreading the chemical elements, triggering the formation of new stars, creating black holes and pulsars. Originally published in 1978 and first published by Cambridge as this revised edition in 1985, is the story of supernovae. It captures the flavour of ancient astronomy and lays out the accidents, coincidences, false leads and flashes of inspiration that followed as astronomers grasped the implications behind the rare appearance of supernovae. Two supernovae, seen in 1572 and 1604, made scientists aware that the stars changed and could be studied like everything else. Eventually, modern astronomers came to link supernovae with black holes, pulsars, and even with the creation of the chemical elements. The whole entertaining story is told clearly, in non-technical language, showing the triumph of human imagination as we discovered our place in the universe.

This book journeys into one of the most fascinating intellectual adventures of recent decades - understanding and exploring the final fate of massive collapsing stars in the universe. The issue is of great interest in fundamental physics and cosmology today, from both the perspective of gravitation theory and of modern astrophysical observations. This is a revolution in the making and may be intimately connected to our search for a unified understanding of the basic forces of nature, namely gravity that governs the cosmological universe, and the microscopic forces that include quantum phenomena. According to the general theory of relativity, a massive star that collapses catastrophically under its own gravity when it runs out of its internal nuclear fuel must give rise to a space-time singularity. Such singularities are regions in the universe where all physical quantities take their extreme values and become arbitrarily large. The singularities may be covered within a black hole, or visible to faraway observers in the universe. Thus, the final fate of a collapsing massive star is either a black hole or a visible naked singularity. We discuss here recent results and developments on the gravitational collapse of massive stars and possible observational implications when naked singularities happen in the universe. Large collapsing massive stars and the resulting space-time singularities may even provide a laboratory in the cosmos where one could test the unification possibilities of basic forces of nature.

ESO's new and exciting telescope, the VLT in Chile, will certainly bring a host of new results in optical astronomy for the years to come. This workshop surveys a large variety of possible observations and the needed instrumentation. It is an exciting overview of front research in astronomy rarely published before. The book covers the whole gamut of optical-IR astronomy from the solar system, search for planets in nearby stars, physics of galactic stars and clusters, galactic structure, structure of nearby galaxies, AGN and quasars, clusters of galaxies, to large structure and cosmology. Furthermore it summarizes the two panel discussions.

The ESO jIAC Workshop on Quasar Hosts was held in Puerto de la Cruz, Tenerife, from 24 to 27 September 1996 in the Conference Centre of the Ca- bildo Insular de Tenerife. The four days of the meeting were filled with fasci- nating new results and interesting discussions, and ranged from the centre of our own galaxy to some of the most distant objects known in the universe. Quasar Host studies are going through an exciting time, and are benefiting from new facilities, including the refurbished HST and the Keck, and from novel techniques, including adaptive optics and deconvolution methods. We also saw the first of hopefully many results from the ISO satellite. These re- sults were presented during the many sessions and discussed in the gardens over coffee, and on the bus during our tour of the Canaries Observatories. We would very much like to thank the secretaries of ESO and lAC, Christina Stoffer, Pamela Bristow, Monica Murphy, Judith de Araoz, and Beatriz Mederos, who we depended on for their expertise and efficiency. Our colleagues on the scientific organising committee, Phil Crane, Bob Fosbury, Marie-Helene Ulrich, Peter Shaver and Jose Rodriguez-Espinosa, deserve considerable thanks for their contributions to the programme. We must also thank the local organising committee, Fernando Cabrera- Guerra, Monica Murphy, Ismael Perez-Fournon, Ana Perez-Garcia, Luis Ramirez-Castro, and Montserrat Villar-Martin, for all their efforts in making sure things ran smoothly on the day.

An exploration of the intersection of particle physics, astrophysics, and cosmology known as astroparticle physics. Extreme electromagnetic conditions present in puslars and other stars allow for investigations of the role of quantum processes in the dynamics of astrophysical objects and in the early Universe. Based in part on the authors' own work, this book systematically describes several methods of calculation of the effects of strong electromagnetic fields in quantum processes using analytical solutions of the Dirac equation and Feynmann diagrams at both the loop and tree levels. The consideration is emphasized at the two limiting cases: the case of a very strong magnetic field, and the case of a crossed field. The presentation will appeal to graduate students of theoretical physics with prior understanding of Quantum Field Theory (QFT) and the Standard Model of Electroweak Interactions, as well as specialists in QFT wishing to know more about the problems of quantum phenomena in external electomagnetic fields.

The"4thCologne-Bonn-ZermattSymposium: TheDenseInterstellarMedium in Galaxies" took place in Zermatt, Switzerland, from September 22nd to 26th, 2003. This symposium continued the series of conferences on the dense interstellar medium which has been organized every 5 years since 1988 by the I. Physikalisches Institut der Unversit] at ] zuKoln. ] Re?ecting the by now well established and fruitful collaboration between the MPI ffur ] ] Radioastronomie, the Radioastronomisches Institut der Universit] at ] Bonn and the I. Physikal- ches Institut der Universit] at ] zu Koln ] in the context of the Sonderforschun- bereich 494 "The Evolution of Interstellar Matter: THz-Spectroscopy in the Laboratory and in Space," the symposium is now organized jointly by these three institutes. The conference covered a wide range of topics: starting at the largest scales and earliest times in the history of the Universe, it focussed next on galaxy evolution and their structure and dynamics. New and very exciting results on the black hole in the center of the Milky Way and the violent ISM in its immediate vicinity were presented. It continued on the cosmic cycle of star formation and evolution, and reached down to the microphysical p- cesses determining the physical and chemical conditions of the interstellar matter as the important agent for this cosmic cycle."

Chondrules in primitive meteorites have excited and challenged scientists since they were first described nearly 200 years ago. Chondrules were made by some pervasive process in the early solar system that formed melted silicate droplets. This 1996 text was the first comprehensive review of chondrules and their origins since a consensus developed that they were made in the disk of gas and solids that formed the Sun and planets 4.5 billion years ago. Fifty scientists from assorted disciplines have collaborated to review how chondrules could have formed in the protoplanetary disk. When and where in the disk did they form? What were they made from and how fast were they heated and cooled? What provided the energy to melt chondrules - nebular shock waves, lightning discharges, protostellar jets? Following an exciting international conference in Albuquerque, New Mexico, the latest answers to these questions are presented in thirty-four articles.

The stars that form a halo around our Galaxy are intriguing; they have abundances of elements that suggest they are old. The properties of these 'hot stars' and similar stars in other galaxies challenge the well-established theory of stellar evolution in many ways. Studying the collective properties of these stars provides important input to many areas of astrophysics - including the formation of our Galaxy, stellar evolution and the stellar populations of other galaxies. The study of hot stars in the halo of our Galaxy is undergoing an exciting renaissance owing to important new observations with the Hubble Space Telescope and ASTRO1 and to techniques recently developed for ground-based observations. Advances in computers have also recently led to a far more detailed and complete theoretical understanding of stellar evolution. This volume, first published in 1994, draws together the proceedings of a conference held in Union College, New York, which gathered experts in the field in question.

The standard cosmological picture of our Universe emerging from a 'big bang' leaves open many fundamental questions which string theory, a unified theory of all forces of nature, should be able to answer. This 2007 text was the first dedicated to string cosmology, and contains a pedagogical introduction to the basic notions of the subject. It describes the possible scenarios suggested by string theory for the primordial evolution of our Universe. It discusses the main phenomenological consequences of these scenarios, stresses their differences from each other, and compares them to the more conventional models of inflation. The book summarises over 15 years of research in this field and introduces advances. It is self-contained, so it can be read by astrophysicists with no knowledge of string theory, and high-energy physicists with little understanding of cosmology. Detailed and explicit derivations of all the results presented provide a deeper appreciation of the subject.

High-energy astrophysics covers cosmic phenomena that occur under the most extreme physical conditions. It explores the most violent events in the Universe: the explosion of stars, matter falling into black holes, and gamma-ray bursts - the most luminous explosions since the Big Bang. Driven by a wealth of observations, there has been a large leap forward in our understanding of these phenomena. Exploring modern topics of high-energy astrophysics, such as supernovae, neutron stars, compact binary systems, gamma-ray bursts, and active galactic nuclei, this 2007 textbook is ideal for undergraduate students in high-energy astrophysics. It is a self-contained, relevant overview of this exciting field of research. Assuming a familiarity with basic physics, it introduces all other concepts, such as gas dynamics or radiation processes, in an instructive way. An extended appendix gives an overview of some of the most important high-energy astrophysics instruments, and each chapter ends with exercises.

What is unorthodox in this book? Much has happened in the last few years, especially in terms of the somewhat surpris ing rate at which the theories presented herein have been gaining increasing acceptance and support even by the most skeptical professionals. Nevertheless, the purpose of this up-dated Preface is not to tell the biographical and acceptance story behind this book, but to bring together some non-physical and non technical conclusions for those readers who find the physico-mathematical sections of this book too difficult to follow. A secondary purpose is to present here some newer conclu sions, especially in general philosophy and in aesthetics. Yet, the main physico philosophical conclusions presented in this book are not to be summarized here. For that purpose one must tum to the text itself. * * * The theories presented here have been developed in total isolation. They were never presented in "professional conferences," as most current writers do. Whether or not that was important remains to be seen. Hence, all I can state to critics and enthusiastic follow ers alike is the fact that I do not belong to any 'formal discipline', 'pressure group', or 'pro fessional organization'."

"Stellar Physics" is a an outstanding book in the growing body of literature on star formation and evolution. Not only does the author, a leading expert in the field, very thoroughly present the current state of knowledge on stellar physics, but he handles with equal care the many problems that this field of research still faces. A bibliography with well over 1000 entries makes this book an unparalleled reference source.
"Stellar Evolution and Stability" is the second of two volumes and can be read, as can the first volume "Fundamental Concepts and Stellar Equilibrium," as a largely independent work. It traces in great detail the evolution of protostars towards the main sequence and beyond this to the last stage of stellar evolution, with the corresponding vast range from white dwarfs to supernovae explosions, gamma-ray bursts and black hole formation. The book concludes with special chapters on the dynamical, thermal and pulsing stability of stars.

This second edition is carefully updated in the areas of pre-supernova models, magnetorotational supernovae, and the theory of accretion disks around black holes. Additional sections have been added on strange quark stars, jet formation and collimation, radiation-driven winds in strong gravitational fields and gamma-ray bursts.

Understanding the formation of objects at all scales in the universe, from galaxy clusters to stars and planets, is a major problem in modern astrophysics, and one of the most exciting challenges of twenty-first century astronomy. Even though they are characterized by different scales, the formation of planets, stars and galaxies share many common physical processes and are rooted in the same underlying domains of physics. This unique reference for graduate students and researchers in astrophysics was the first to cover structure formation on various scales in one volume. This book gathers together extensive reviews written by world experts in physics and astrophysics working in planet, star and galaxy formation, and related subjects. It addresses current issues in these fields and describes the recent observational status and theoretical and numerical methods aimed at understanding these problems.