The recent meeting of the world's white dwarf specialists was held in Leicester, in July 1992, reporting on the wealth of astronomical data that has been made available from a new generation of space-based observatories and recent theoretical advances which are essential for interpretation of the results. Astronomers now have access to previously unavailable spectral ranges and dramatically improved sensitivity in those wavebands already explored. Results from the ROSAT all-sky survey, Hubble Space Telescope, Hopkins Ultraviolet Telescope and the Colorado Rocket-borne Spectrometer shed new light on the composition of white dwarfs and their evolution. Considerable progress has been made in understanding the internal structure of white dwarfs with asteroseismological techniques which are outlined in several papers. New observational results, which utilize this theoretical work are also presented. This text is suitable for graduate students and postdoctoral researchers interested in isolated white dwarfs or binary systems containing a white dwarf component.

The purpose of this book is to give a detailed description of the planetary nebulae including the relevant astronomical observations and their interpretation. Considerable attention is given to the evolution of these objects as well as to their physical characteristics. I t is hoped that the book be useful to both advanced research workers and to students with some background in astronomy. In this regard, the book should serve as a text as well as a reference work. The many tables included are expected to be useful for both purposes. The references are generally not included in the text except for historical purposes in an effort to improve readability. References are given at the end of each chapter together with sufficient text to describe their content. No attempt has been made to make the list of references complete; on the contrary it has generally been limited to the most recent literature on the subject which in turn refers to earlier research. Again, exceptions have been made for references of historical interest.

These proceedings of a workshop held at Isle-aux-Coudres, Quebec, Canada in August 1993, provide an assessment of a fundamental subject in modern stellar astrophysics. Hot, luminous stars play a crucial role in the rapid recycling of matter in dense regions of the Universe. The most luminous objects generate the strongest outflows of material, which in turn have a profound impact on both the interstellar medium and the underlying stars themselves. However, recent observational and theoretical advances have shown that these outflows are highly unstable and inhomogeneous. These characteristics constitute a fundamental property of the outflows that can no longer be disregarded. This text provides an assessment of this important phenomenon from both an observational and a theoretical perspective. It includes up-to- date discussions of the observational diagnostics of time-dependent stellar-wind structure, the theoretical understanding of the origin of such structures, and its consequences for the process of mass loss via stellar winds.

This thesis represents the first wide-field photometric and spectroscopic survey of star clusters in the nearby late-spiral galaxy M33. This system is the nearest example of a dwarf spiral galaxy, which may have a unique role in the process of galaxy formation and evolution. The cold dark matter paradigm of galaxy formation envisions large spiral galaxies, such as the Milky Way, being formed from the merger and accretion of many smaller dwarf galaxies. The role that dwarf spiral galaxies play in this process is largely unclear. One of the goals of this thesis is to use the star cluster population of M33 to study its formation and evolution from its early stages to the present. The thesis presents a new comprehensive catalog of M33 star clusters, which includes magnitudes, colors, structural parameters, and several preliminary velocity measurements. Based on an analysis of these data, the thesis concludes that, among other things, the evolution of M33 has likely been influenced by its nearby massive neighbor M31.

Stellar astrophysics still provides the basic framework for deciphering the imprints left over by the evolving universe on all scales. Advances or shortcomings in the former field have direct consequences in our ability to understand the global properties of the latter.

This volume contains the most recent updates on a variety of topics that, though independent by themselves, are inevitably connected on a cosmological scale. These include comprehensive articles by leaders in fields extending from stellar atmospheres through properties of the stellar component in the Milky Way up to the stellar environment in high redshift galaxies.

The wide coverage of astrophysical themes makes this volume very valuable for researchers and Ph.D. students in astrophysics.

Colloquium No. 72 of the International Astronomical Union covered many observations and theoretical developments in the field of cataclysmic variables and related objects. Much time was devoted to discussions and we made an effort to include as much of the discussions material as possible in the proceedings. The Local Organizing Committee would like to thank; The International Astronomical Union for travel grants The Israel Academy of Sciences for financial support The Technion-Israel Institute of Technology for financial support and assistance Bank Leumi Le-Israel for a generous support We also thank the Dean of the Faculty of Physics, our colleagues and students for their assistance. MARIO LIVIO GIORA SHAVIV SCIENTIFIC ORGANIZING COMMITTEE B. Warner (Chairman), G.T. Bath, D. Crampton, J.E. Pringle, E.L. Robinson, G. Shaviv, R.E. Williams, J. Smak LOCAL ORGANIZING COMMITTEE G. Shaviv (Chairman), A. Finzi, M. Livio, H. Netzer, 0, Sadeh LIST OF PARTICIPANTS BATH, Geoffrey, T. Dept. of Astrophysics, Oxford, England BIANCHINI, Antonio Osservatorio Astronomico, Padova, Italy BROWNLEE, Robert, R. Los Alamos, New Mexico, U.S.A. CHANMUGAM, Ganesh Dept. of Physics and Astronomy, Louisiana State University, U.S.A. COLVIN, Jeff EG&G, Los Alamos, U.S.A. COWLEY, Anne, P. Dominion Astrophysical Observatory, Canada CRAMPTON, David Dominion Astrophysical Observatory, Canada EGGLETON, Peter P. Institute of Astronomy, Cambridge, England EVANS, A. Dept. of Physics, University of Keele, United Kingdom FEINGOLD, Susan J. Dept. of Physics, Technion, Israel FINZI, A.

A leading stellar astronomer summarizes our understanding of supernovae and their interaction with interstellar gas, including the ambient interstellar medium, the gas ejected in the explosion itself, and the gas emitted as stellar wind. She examines the evolution of supernova remnants as they interact with the gas and considers the role of supernovae and stellar wind in the physical state of the interstellar medium. Essential reading for specialists in supernovae and stellar evolution.

Recent advances in our understanding of instabilities in galactic type systems have led to an unravelling of some of the mysteries of what determines the form galaxies take. This book focuses on the mathematical development of the subject, assuming no prior knowledge of it, with a strong emphasis on the underlying physical interpretation. This framework is used to discuss the most relevant instabilities which are believed to be closely involved in the way galaxies are formed, in a model independent manner. The relevant observed properties of galaxies that may be used to establish the role of these physical mechanisms are discussed. The book also includes a chapter discussing numerical simulation techniques, with attention paid to their limitations and to recent advances in this approach. It is demonstrated that recent developments in computer hardware enable a detailed comparison of simulations with analysis. Thus the simulations extend our physical understanding beyond the limitations of the analysis. The book is intended for use by postgraduate students and researchers in the areas of cosmology, extragalactic astronomy and dynamics.

Star clusters are at the heart of astronomy, being key objects for our understanding of stellar evolution and galactic structure. Observations with the Hubble Space Telescope and other modern equipment have revealed fascinating new facts about these galactic building blocks. This book provides two comprehensive and up-to-date, pedagogically designed reviews on star clusters by two well-known experts in the field. Bruce Carney presents our current knowledge of the relative and absolute ages of globular clusters and the chemical history of our Galaxy. Bill Harris addresses globular clusters in external galaxies and their use as tracers of galaxy formation and cosmic distance indicators. The book is written for graduate students as well as professionals in astronomy and astrophysics.

Proceedings of IAU Symposium No. 50, held in Villa Carlos Paz, Argentina, October 18-24, 1971

The atmospheres of many stars have chemical compositions that are significantly different from that of the interstellar medium from which they are formed. This symposium considered all kinds of late-type stars showing altered compositions, the carbon stars being simply the best-known of these. All stages of stellar evolution from the main sequence to the ejection of a planetary nebula were considered, with emphasis on the changes that occur on the asymptotic giant branch. The spectroscopic properties of the photospheres and circumstellar envelopes of chemically-peculiar red giant stars, their origins via single-star evolution or mass transfer in binary systems, and the methods currently used to study them were all discussed in detail. This volume includes the full texts of papers given orally at the symposium and abstracts of the posters.

The term proto-planetary nebulae (PPNe), in the context of the late stages of stellar evolution, was created just over 20 years ago, to express the belief that in the near future these objects will become planetary nebulae (PNe). The first proto-planetary nebulae (also called post-Asymptotic Giant Branch or post-AGB objects) were discovered in the mid-1970s in the course of the Air Force Sky Survey. Investigation of this phase of stellar evolution developed very rapidly in the 1980s after the IRAS mission when it became clear that proto-planetary nebulae emit a significant part of their energy in the mid- and far-infrared. A new impetus in this field began in the 1990s with high spatial resolution imaging in mid-infrared and optical wavelengths. Evidence has been found that proto-planetary nebulae (at least their central parts) are quite asymmetric while shells of AGB stars display spherical shapes. The most intriguing challenge now is to understand which physical processes are dominant during formation and evolution of proto-planetary nebulae. Is it magnetic field, evolution in binary systems, planets, axisymmetric superwind mass loss and its further shaping by fast wind, collimated jets interacting with a spherically symmetric AGB remnant or maybe an interplay between these different processes? Another challenge is to explain why the mass loss process near the end of the AGB evolution is modulated on timescales of a few hundred years. The model presented during this workshop seems to be very promising in this respect.

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."

This book is the result of a meeting held in August, 1986 in Irsee, West Germany. As the title suggests, the aim of the meeting was to discuss physical processes in interstellar clouds, determine the current status, aims and future direction of the research in this area. Interstellar clouds contain nearly all the mass of diffuse gas in our galaxy, some 10% of the total galactic mass. They represent the birth site for stars and the final "dumping ground" for matter ejected from stars (winds, ex plosive ejecta) and thus play an integral part in the galactic recycling of material. Not only are the clouds important for the structure and evolution of our galaxy, they are also interesting objects of study "per se." Because of their vast scales (up to about 100 parsec), extreme temperatures (as low as about lOOK), and long life 8 times (estimated a about 10 years) a number of physical and chemical processes occur in these environments, which we are not able to study elesewhere, certainly not in laboratories. It is for this reason that the meeting, and hence this book, was organized in such a way that firstly the latest observational results were sum m ized, going from the global, large scales, to finer details and dynamics, then progressing onwards to the processes -dynamical, chemical, electromagnetic, etc."

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."

Starbursts are important features of early galaxy evolution. Many of the distant, high-redshift galaxies we are able to detect are in a starbursting phase, often apparently provoked by a violent gravitational interaction with another galaxy. In fact, if we did not know that major starbursts existed, these conference proceedings testify that we would indeed have difficulties explaining the key properties of the Universe! These conference proceedings cover starbursts from the small-scale star-forming regions in nearby galaxies to galaxy-wide events at high redshifts; one of the major themes of the conference proved to be "scalability," i.e., can we scale up the small-scale events to describe the physics on larger scales. The key outcome of this meeting a" and these proceedings a" is a resounding "yes" as answer to this fundamental, yet profound question. The enhanced synergy facilitated by the collaboration among observers using cutting-edge ground and space-based facilities, theorists and modellers has made these proceedings into a true reflection of the state of the art in this very rapidly evolving field.

Ample space is provided for summaries of the large number of talks by experts in the field, while the high-quality poster contributions are all contained on the accompanying CD-ROM, thus enhancing the information content.

Proceedings of IAU Symposium No. 76 held at Cornell University, Ithaca NY, USA, 6-10 June 1977

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.

Many important observational clues about our understanding of how stars and planets form in the interior of molecular clouds have been amassed using recent technological developments. ESO's very large telescope promises to be a major step forward in the investigation of stellar nurseries and infant stars. This volume collects papers from the leaders in this very timely field of astrophysical research. It presents theoretical and a host of observational results and many papers show the plans for future observations.

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.

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.

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.

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.

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."