This book is the proceedings of a workshop on stellar continuum radio astronomy that was held in BoUlder, Colorado on August 8-10, 1984. Although it was originally intended to be a small workshop with participants mainly from North America, it evolved to a workshop with 72 partiCipants from twelve countries (U.S.A. 52, Canada 3, the Netherlands 3, United Kingdom 3, Australia 2, Ireland 2, Italy 2, France 1, Mexico 1, Switzerland 1, West Germany 1, and U.S.S.R. 1). This workshop was sponsored by the Joint Institute of Laboratory Astrophysics (JILA) and the University of Colorado. In order to preserve a workshop atmosphere, while still presenting both extensive reviews and contributed papers, an experimental format was adopted. All contributed papers related to the topiCS of the day were presented in poster form in the early morning and were accessible all day. During each morning (or afternoon) session review papers were presented, followed by a coffee break in the poster area adjacent to the conference room. Then the review papers and contributed papers were discussed for roughly one and a half hours. The last session was devoted to invited panel papers and discussion of current and future problems in the field of stellar radio astronomy.

The Andromeda Galaxy, or M31, is an attractive galaxy for astronomers. It is close to us, it is of about the size of our galaxy, it provides some intriguing observational puzzles because the galaxy is nearly edge-on, and many objects can be studied in detail, because they are still sufficiently bright. With the current developments in instrumentation with which increasingly detailed studies of the Andromeda Galaxy can be made, this book provides a solid foundation for the start of new observations. This book is a mine of information about M31. It can be used as a reference by insiders, and at the same time it provides easy access for newcomers to the field.

Highly ionized atoms in the general interstellar gas of the galactic disk were first detected through interstellar absorption line observations of 0 VI with the Copernicus satellite (Rogerson et al. 1973). Survey measurements by Jenkins (1978) of interstellar 0 VI absorption toward 72 stars demonstrated the general presence of 0 VI in the interstellar medium of the galactic disk. This researcIi. and parallel observational studies of the soft X-ra}' background (Williamson et al. 1974; McCammon et al. 1983; Marshall and ClarK 1984) provided direct evidence for the existence of hot low density gas in the mterstellar medium of the galactic disk. The extension of the aDsorption line studies to the distant gas of the galactic halo required the launch of the International Ultraviolet Explorer (IUE) satellite in 1978. The first measures of highly ionized gas m the galactic halo were obtained with the IDE when it was used to record high resolution spectra of bright stars in the Large Magellanic Cloud (Savage and de Boer 1979). Those early spectra revealed the presence of absorption by Si IV and C IV in the galactic nalo and have been followed by a number of surveys with IUE of nighly ionized gas in the galactic disk and halo (Savage and de Boer 1981; Pettini and West 1982; Savage and Massa 1987). The study of UV emission from highly ionized gas in the halo has progressed more slowly because of the intrinsic faintness of the emission.

IAU Symposium No. 134 on Active Galactic Nuclei was hosted by the Lick Observatory, as part of the celebration of its centennial, for the Observatory went into operation as part of the University of California on June 1, 1888. Twenty years later, in 1908, Lick Observatory graduate student Edward A. Fath recognized the unusual emission-line character of the spectrum of the nucleus of the spiral "nebula" NGC 1068, an object now well-known as one of the nearest and brightest Seyfert galaxies and active galactic nuclei. Ten years after that, and seventy years before this Symposium, Lick Observatory faculty member Heber D. Curtis published his description of the "curious straight ray" in M 87, "apparently connected with the nucleus by a thin line of matter," which we now recognize as an example of one of the jets which are the subject of so much current AGN research. The symposium was held at Kresge College on the campus of the University of California, Santa Cruz, only a short walk through the redwood groves to the Lick Observatory offices. A total of 232 astronomers and astrophysicists from 24 countries attended and took part in the Symposium. About 200 more had applied to come, but could not be accepted in order to keep the meeting at a reasonable size. Most of the participants lived in the Kresge College apartments immediately adjacent to the Kresge Town Hall in which the oral sessions took place.

It is not an exaggeration to say that one of the most exciting predictions of Einstein's theory of gravitation is that there may exist "black holes" putative objects whose gravitational fields are so strong that no physical bodies or signals can break free of their pull and escape. The proof that black holes do exist, and an analysis of their properties, would have a significance going far beyond astrophysics. Indeed, what is involved is not just the discovery of yet another even if extremely remarkable, astro physical object, but a test of the correctness of our understanding of the properties of space and time in extremely strong gravitational fields. Theoretical research into the properties of black holes, and into the possible corol laries of the hypothesis that they exist, has been carried out with special vigor since the beginning of the 1970's. In addition to those specific features of black holes that are important for the interpretation of their possible astrophysical manifestations, the theory has revealed a number of unexpected characteristics of physical interactions involving black holes. By the middle of the 1980's a fairly detailed understanding had been achieved of the properties of the black holes, their possible astrophysical manifestations, and the specifics of the various physical processes involved. Even though a completely reliable detection of a black hole had not yet been made at that time, several objects among those scrutinized by astrophysicists were considered as strong candidates to be confirmed as being black holes."

This thesis explores the possibility of searching for new effects of dark matter that are linear in g, an approach that offers enormous advantages over conventional schemes, since the interaction constant g is very small, g<<1. Further, the thesis employs an investigation of linear effects to derive new limits on certain interactions of dark matter with ordinary matter that improve on previous limits by up to 15 orders of magnitude. The first-ever limits on several other interactions are also derived. Astrophysical observations indicate that there is five times more dark matter-an 'invisible' form of matter, the identity and properties of which still remain shrouded in mystery-in the Universe than the ordinary 'visible' matter that makes up stars, planets, dust and interstellar gases. Conventional schemes for the direct detection of dark matter involve processes (such as collisions with, absorption by or inter-conversion with ordinary matter) that are either quartic (g4) or quadratic (g2) in an underlying interaction constant g.

This volume presents the edited lecture notes of the First JETSET School on Jets from Young Stars: Models and Constraints, held by the Marie Curie Research and Training Network on JET Simulations, Experiments and Theory. The first half of the book is devoted to general observational constraints. The second section is devoted to theoretical knowledge of magneto-hydrodynamic processes pertinent to the jet launching mechanism in young stars.

The imaging process in stellar interferometers is explained starting from first principles on wave propagation and diffraction. Wave propagation through turbulence is described in detail using Kolmogorov statistics. The impact of turbulence on the imaging process is discussed both for single telescopes and for interferometers. Correction methods (adaptive optics and fringe tracking) are presented including wavefront sensing/fringe sensing methods and closed loop operation. Instrumental techniques like beam combination and visibility measurements (modulus and phase) as well as Nulling and heterodyne interferometry are described. The book closes with examples of observing programmes linking the theory with individual astrophysical programmes.

The mono graph contains 8 chapters, and their contents cover all principal aspects of the problem: 1. Introduction and brief his tory ofthe radiation problem and background information ofradiation hazard in the near-Earth and interplanetary space. 2. General description of radiation conditions and main sources of charged partic1es in the Earth's environment and interplanetary space, effects of space environment on spacecraft. 3. Basic information about physical conditions in space and main sources of charged particles in the Earth's environment and interplanetary space, in the context of "Space W eather" monitoring and prediction. 4. Trapped radiation belts of the Earth (ERB): theory of their origin, spatial and temporal dynamics, and experimental and statistical models. 5. Galactic cosmic rays (GCR): variations of energetic, temporal and spatial characteristics, long-term modulation, and anomalous cosmic ray (ACR) component, modeling oftheir dynamics. 6. Production of energetic particles (SEPs) at/ne ar the Sun: available databases, acceleration, propagation, and prediction of individual SEP event, statistical models of solar cosmic rays (SCR). 7. Existing empirical techniques of estimating, prediction and modeling of radiation hazard, methodical approaches and constraints, some questions of changes in the Earth's radiation environment due to changes of the solar activity level. 8. Unresolved problems of radiation hazard prediction and spacecraft protection, radiation experiments on board the spacecraft, estimating of radiation conditions during interplanetary missions. Space does not allow us to explain every time the solar-terrestrial and radiation physics nomencIature used in current English-language literature.

Neutron stars are the densest observable bodies in our universe. Born during the gravitational collapse of luminous stars - a birth heralded by spectacular supernova explosions - they open a window on a world where the state of the matter and the strengths of the fields are anything but ordinary. This book is a collection of pedagogical lectures on the theory of neutron stars, and especially their interiors, at the forefront of current research. It addresses graduate students and researchers alike, and should be particularly suitable as a text bridging the gap between standard textbook material and the research literature.

Our knowledge of the distribution and properties of the small solid particles within the solar system continues to improve rapidly. Much of the progress is due to observations from spacecraft which offer completely new locations from which to view phenomena such as the zodiacal light. In combination with ground-based observations and improved theoretical models, a picture now emerges with a clarity un attainable even a few years ago. The need for a survey of the situation was recognized in 1976 and, at meetings of COSPAR and the International Astronomical Union in that year, planning began for a symposium to be held in 1979 at a time and place convenient for those attending the IAU General Assembly in Montreal. The result was IAU Symposium No. 90, "Solid Particles in the Solar System," held at the University of Ottawa, from August 27 to 30, 1979. This volume includes eleven invited papers intended to survey par ticular areas of the overall subject and numerous contributed papers providing more detail on specific problems. We hope the combination will prove valuable to both the general reader interested in the current picture of the particles in interplanetary space and also to the specialist involved in research in the field."

The idea of this colloquium was first put forward by Prof. P. Keenan when he visited the Centre de Donnees Stellaires, in September 1982. Dr. A. Florsch, Director of the Strasbourg Observatory, kindly accepted to field it at Strasbourg. The scientific organization of the colloquium was in charge of a Committee chaired by Prof. P.C. Keenan and composed by M. Feast, A. Florsch, B. Gustafsson, D. Harmer, M. Jaschek (secretary), R. McClure, A. Maeder, W. Straizys and T. Tsuji. The members of the Committee helped to translate the idea into a very successful meeting. It should be added that this colloquium was the first meeting devoted to late-type peculiar stars. The program was organized by sessions devoted to the following topics : taxonomy, photometric properties, distribution and space motions, chemical com- position, model atmosphere, binary systems and evolutionary tracks. Each session started with a review paper, followed by contributed papers presented as posters. The different sessions were chaired by W. Bidelman, R. Cayrel, Ch. Cowley, A. Heck, H.R. Johnson, J.P. Kaufmann and T. Tsuji, who did an excellent job. The President of the "Louis Pasteur University of Strasbourg", Prof. H. Duranton, welcomed the participants to the University where the sessions were held; Dr. A. Florsch welcomed the participation on be.balf of the French astrono- mical community and Prof. P. Keenan spoke on behalf on the Scientific Organizing Committee.

This volume offers a background in modern high spatial resolution techniques, illustrating how such methods have impacted on our understanding of young stars. It provides hands-on insight into observing from space as well as the ground, the use of interferometers at millimeter and infrared wavelengths, image analysis and spectral diagnostic techniques, and High Angular Resolution studies of the inner regions of circumstellar disks that play a fundamental role in jet launching.

IAU symposium 165 'Compact Stars in Binaries' was held from 15 through 19 August 1994, as part of the 22nd General Assembly of the IAU in The Hague. The symposium, supported by IAU Commissions 35,37,44 and 48, and co-sponsored by Commission 42, was attended by about 400 to 500 participants. This symposium received support from: - The International Astronomical Union; - The Royal Netherlands Academy of Sciences; - The Netherlands Ministery of Education and Science; - The Leids Kerkhoven Bosscha Fonds; - The Stichting Fysica. The field of compact stars in binaries is one of the most active areas of present-day astrophysics. An absolute highlight of the last few years was the 1993 Nobel Prize of physics, awarded to Taylor and Hulse for their discovery of the binary pulsar PSR 1913+ 16, and the measurement of the orbital decay of this system due to the emission of gravitational waves. The aim of the organizers of the symposium was to present an overview of the most significant observational discoveries of the past decade, in com bination with a review of the most important theoretical developments. We were very happy that most of the world's leading experts in observation and theory were present at the symposium to review the various aspects of the subject. The contents of their oral presentations are now published in the form of these proceedings, which we expect to become an important source of reference for the coming years."

Proceedings of International Meeting held in Trieste, Italy, April 10-13, 1985

This book summarizes the gathering of information on and the growing understanding of M33 from the 1920s, when Hubble first determined its true nature, to the 21st century, when the Hubble Telescope probed deeply into its many secrets. With its regular symmetrical spiral structure, and its being not tilted too much and near enough to allow detailed studies of its stars, M33 is well-suited for the study of a typical spiral galaxy. In this work, Paul Hodge places current research on M33 (and similar galaxies) in both historical and global perspectives. The book is written in a language accessible for specialists and non-specialists, for professional and amateur astronomers, for scientists and the curious public and, most importantly, for students.

This NATO AS was the third in the series of Advanced Study Institutes on neutron stars, which started with 'Timing Neutron Stars', held in Qe me near izmir, Turkey (April 1988), followed by 'Neutron Stars, an Interdis ciplinary Subject', held in Agia Pelagia on the island of Crete (September 1990). The first school centered on our main observational access to neu tron stars, i. e. the timing of radio pulsars and accretion powered neutron stars, and on what timing of neutron stars teaches us of their structure and environment. The second school had as its theme the interplay between diverse areas of physics which find interesting, even exotic applications in the extreme conditions of neutron stars and their magnetospheres. As the field has developed, with the number of observed neutron stars rapidly in creasing, and our knowledge of many individual neutron stars getting deeper and more detailed, an evolutionary picture of neutron stars has started to emerge. This led us to choose 'The Lives of the Neutron Stars' as the uni fying theme of this third Advanced Study Institute on neutron stars. Different types of neutron star activity have been proposed to follow one another in stages during the lives of neutron stars in the same basic population; the evolutionary connection between low-mass X-ray binaries and millisecond radio pulsars is perhaps the prime example."

''An atteJDpt has been made to cOll1PlJte the numbers of certain JI10lecules in interstellar space , . . . . A search for the bands of CH, O/{, DR, en and C2 would appear to be proIDising" P Swings and L Rosenfeld Astrophysical Journal 86,483(1937) This may have been the first attempt at modelling interstellar chemistry. As with models today, the methods used lacked reliability, but the speculation was impressive! Mark Twain might well have said of this infant subject "One gets such wholesale returns of conjecture out of such a trifling investment of fact". The detection of unidentified lines around the period that Swings and Rosenfeld were writing provoked much interest, but even the most optimistic speculator could hardly have imagined developments which would occur during the next 50 years. By 1987 about 70 varieties of molecule had been identified in the interstellar and circumstellar regions, They range in complexity from simple diatomics such as H2 and CO to such species as ethanol C2HeDH, acetone (CHs)2CO, and the largest interstellar molecule detected so far, cyano-penta acetylene HC11N, The study of these molecules in astronomy has developed enormously, especially over the last 20 years, and is now codified in the new subject of astrochemistry, That such a variety of chemical species should exist in tenuous regions of the Galaxy is fascinating.

Active Galactic Nuclei radiate over the electro-magnetic spectrum from radio waves to gamma rays. Understanding the physics of these objects therefore requires the synthesis of results from many different domains of Astronomy. It was the aim of the conference "Active Galactic Nuclei across the Electromagnetic Spectrum" to provide a forum where this exchange could take place. Some 300 astronomers participated to the conference, 250 of them presented results either as oral papers or in the form of posters. Observations in all domains of the electro magnetic spectrum in which astronomical observations can be made from the ground or from space were presented. Many theoretical contributions were also given. There has been a tremendous growth in the number and quality of Astronomical obser vations in many spectral domains over the past several years. Students of Active Galactic Nuclei have been particularly keen to make use of the available facilities (both space born and on the ground), often in a very organised way, in order to obtain repeated simultane ous data covering large bands of the spectrum. This approach has produced a qualitatively new set of data for understanding the physics of Active Galactic Nuclei. The task of the meeting was to review this data in a coherent way."

IAU Symposium 135 on Interstellar Dust was hosted and co-sponsored by NASA's Ames Research Center from July 26-30, 1988. The symposium was held at the lovely campus of Santa Clara University situated around the historic Santa Clara Mission in California. The meeting was made possible by generous grants from the Astron omy and Relativity Branch of the National Aeronautics and Space Administration and the Galactic Astronomy Program of the National Science Foundation. The International Astronomical Union provided travel grants to a few participants from countries with limited travel funds. We are particularly grateful for the support and services rendered by the dedicated staff at NASA's Ames Research Center and to the" SET! Institute for professionally and expeditiously administering the U.S. grants. This symposium brought together 199 scientists representing 19 different coun tries. The wide range of interest and expertise of the participants - all in some way related to interstellar dust - is reflected in the great variety of topics that were discussed during the symposium ranging from UV, visible and IR observations of interstellar extinction to quantum-statistical calculations of the IR emission from highly vibrationally excited molecules. During the course of the meeting, 41 invited review papers and 140 contributed papers were presented. This book is a collection of the invited review papers. The contributed papers have been published in a companion volume, NASA CP-3036, available from National Technical Information Service, Springfield, Virginia 22161, USA.

This volume is the documentation of the first Course on 'Neutron Stars, Active Galactic Nuclei and Jets', of an Erice School with a wide astro physical scope. The choice of the subject was made because of an apparent similari ty - stressed already at earlier meetings - of four classes of astrophy sical jet sources: Active Galactic Nuclei, Young Stellar Objects, Binary Neutron Stars and Binary White Dwarfs. They share important properties such as their morphology, high variability and large veloci ty gradients as well as - with some inference - their broad spectrum, hypersonic outflow and core/lobe power ratio. Despite this apparent similarity of the four source classes, quite different models have been put forward for their description: (i) The central engine of active galactic nuclei has been generally thought to be a black hole, in contrast to the central engine of young stellar objects and cometary nebulae which apparently is a pre-T-Tauri star, some six orders of magnitude less compact, and to the central engine of planetary nebulae which mayor may not be a binary white dwarf. (ii) The elongated lobes, or flow patterns, have been often interpreted as highly directional stellar wind outflows whereas in a few well mapped cases, the elongated flow appears to be 'pumped up' through a much narrower channel, or jet, both in the extragalactic and stellar sources."

The theory of stellar atmospheres is one of the most important branches of modern astrophysics. It is first of all a major tool for understanding all aspects of stars. As the physical properties of their outer layers can now be found with high precision, firm conclusions can be drawn about the internal structure and evolution of stars. Moreover, improvements in our knowledge of the chemical composition of stars is shedding new light on the chemical evolution of galaxies and of the Universe as a whole. Because the outer layers of stars are among the best-understood astrophysical objects, the theory of stellar atmospheres plays an important role in the study of many other types of objects. These include planetary nebulae, H II regions, interstellar matter, and objects of interest in high-energy astrophysics, such as accretion disks (close binaries, dwarf novae, cataclysmic variables, quasars, active galactic nuclei), pulsar magnetospheres, and Seyfert galaxies. Finally, as stars provide a laboratory in which plasmas can be studied under more extreme conditions than on earth, the study of stellar atmospheres has strong connections with modern physics. Astronomical observations provided a vital stimulus in the early stages of quantum theory and atomic physics; even today topics such as low-temperature dielectronic recombination develop hand in hand with the interpretation of stellar and nebular spectra. Early work on MHD was similiarly motivated. Many such connections remain to be explored.

Over the last decade we have witnessed a rapid change in our understanding of the late stages of stellar evolution. A major stimulus to this has been the synthesis of observational data from different wavebands of the electromagnetic spectrum. The advent of infrared astronomy has led to the discovery of many luminous. late-type stars obscured by their circumstellar dust envelope. Sources discovered in the IRC and AFGL infrared sky surveys were followed up by radio observa tions, leading to the widespread use of the OH and CO molecules as probes of the circumstellar envelopes. Advances in the technique of aperture synthesis have made possible observations with unprecedent resolving power, both in spectral-line and continuum. The success of the recent IRAS sky survey, with the detection of over 250,000 sources, brings the promise of even more exciting years ahead. This area of astronomical research is also blessed with the close collaboration between theorists and observers. New ideas are constantly being quantitatively tested by new data. Theoretical predictions are eagerly used as guides for further observations. This conference was initiated with the following objective: bring together workers in optical, infrared, radio and theoretical astronomy and let them confront each other. Based on the post-conference res ponses we received, many of the participants have indeed found this Workshop a stimulating experience. The Workshop on the Late Stages of Stellar Evolution was held from 2-5 June 1986 in Calgary, Canada."

Mergers are the mechanisms by which galaxy clusters are assembled through the hierarchical growth of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. Many of the observed properties of clusters depend on the physics of the merging process. These include substructure, shock, intra cluster plasma temperature and entropy structure, mixing of heavy elements within the intra cluster medium, acceleration of high-energy particles, formation of radio halos and the effects on the galaxy radio emission.

This book reviews our current understanding of cluster merging from an observational and theoretical perspective, and is appropriate for both graduate students and researchers in the field.

Simon Murphy's thesis has significant impact on the wide use of the revolutionary Kepler Mission data, leading to a new understanding in stellar astrophysics. It first provides a deep characterisation and comparison of the Kepler long cadence and short cadence data, with particular insight into the Kepler reduction pipeline. It then brings together modern reviews of rotation and peculiarities in A-type stars, and their relationship with the pulsating delta Scuti stars. This is the first combined review of these subjects since the classic monograph by Sydney Wolff, "The A stars," was published three decades ago. The thesis presents a novel technique, Super-Nyquist Asteroseismology, that has opened up the asteroseismic study of thousands of Kepler stars. It shows case studies of delta Scuti stars examining amplitude growth, super-Nyquist pulsation, and pulsation in a high-amplitude, population II SX Phoenicis star in a 343-d binary. This work informs our understanding of the relation of rotation to peculiarity, hence has applications to atomic diffusion theory. This is a brilliant thesis written in an elegant and engaging style.