IAU Symposium No. 121 was hosted by the Byurakan Astrophysical Observatory in Soviet Armenia, almost 30 years after Ambartsumian's pioneering ideas about galaxy activity were first published and almost exactly 20 years after the first Byurakan IAU symposium on nuclear activity (No. 29, "Non-stable Phenomena in Galaxies, May 1966). Although the proceedings of the first Byurakan symposium were not published in English, that conference provided a definitive impulse to the field, as Ambartsumian's ideas had done 10 years earlier. The Byurakan Astrophysical Observatory was thus a particularly appropriate setting for IAU 121. The symposium was also very timely since many new exciting results were presented which will surely revolutionize many of our present ideas about nuclear activity in galaxies and QSO's. The first results of the by now famous Markarian survey were presented by B.E. Markarian in the first Byurakan conference. Unfortunately, his untimely death prevented him from attending the second conference, but the influence of his fundamental work was certainly felt.

Red giant and supergiant stars have long been favorites of professional 6 and amateur astronomers. These enormous stars emit up to 10 times more energy than the Sun and, so, are easy to study. Some of them, specifically the pulsating long-period variables, significantly change their size, brightness, and color within about a year, a time scale of interest to a single human being. Some aspects of the study of red giant stars are similar to the study of pre-main-sequence stars. For example, optical astronomy gives us a tantalizing glimpse of star forming regions but to really investi gate young stars and protostars requires infrared and radio astronomy. The same is true of post-main-sequence stars that are losing mass. Optical astronomers can measure the atomic component of winds from red giant stars that are undergoing mass loss at modest rates 6 (M $ 10- M9/yr.). But to see dust grains and molecules properly, 5 especially in stars with truly large mass loss rates, ~ 10- M9/yr, one requires IR and radio astronomy. As this stage of copious mass loss only lasts for ~105 years one might be tempted to ask, "who cares?".

Proceedings of IAU Symposium No. 95 held in Bonn, Federal Republic of Germany, 26-29 August 1980

All theoretical and observational topics relevant to the understanding of the thermonuclear (Type Ia) supernova phenomenon are thoroughly and consistently reviewed by a panel including the foremost experts in the field. The book covers all aspects, ranging from the observations of SNe Ia at all stages and all wavelengths to the 2D and 3D modelling of thermonuclear flames in very dense plasmas. Scenarios for close binary evolution leading to SNe Ia are discussed. Particular emphasis is placed on the homogeneity vs. diversity of SNe Ia and on their use as standard candles to measure cosmological parameters. The book reflects the recent and very significant progress made in both the modelling of the explosions and in the observational field.

Stellar mass loss is an essential part of the cycling of material from the interstellar medium into stars and back, and must be understood if we are to model processes on galactic to cosmological scales. The study of stellar winds and the effects of stellar mass loss has reached a particularly exciting stage where observational capabilities are increasingly able to provide interesting constraints on models and theories. Recent resu1ts from theoretical and observational work for both hot and cool stars with substantial winds have led to the suggestion that a combination of pulsation with other mechanisms makes for particularly efficient mass loss from stars. This provided the original motivation for the organization of this workshop. The conference was organized along relatively conventional lines according to the types of objects being scrutinized. However the true unity of the proceedings comes from the interplay of the mechanisms involved. For example, for the cool, luminous Mira variables, pulsation leads to shock waves that extend the atmosphere, enhancing dust formation; radiation pressure on dust drives the wind, cooling the atmosphere and in some cases suppressing the shocks. Similarly for the Be stars, both pulsation (in this case, non-radial) and radiation pressure (due to UV resonance lines) are expected to be important, and this expectation is at least qualitatively borne out by the observations.

"If simple perfect laws uniquely rule the universe, should not pure thought be capable of uncovering this perfect set of laws without having to lean on the crutches of tediously assembled observations? True, the laws to be discovered may be perfect, but the human brain is not. Left on its own, it is prone to stray, as many past examples sadly prove. In fact, we have missed few chances to err until new data freshly gleaned from nature set us right again for the next steps. Thus pillars rather than crutches are the observations on which we base our theories; and for the theory of stellar evolution these pillars must be there before we can get far on the right track. " These words written by Martin Schwarzschi1d in his famous book en titled "Structure and Evolution of the Stars"(1958) remind us how necessary and fruitful is the interplay of stellar evolution theory and observations. Clearly, observations are the great censor by their possibility of confirming or contradicting theoretical constructions. In addition, they have a driving role: new and sometimes unexpected facts may give rise to progressive ideas and stimulate further theoretical developments. In turn, theory, in its major role of sifting out and placing the facts in a logical sequence based on physical laws, must also be predictive and indicate new and pertinent observations to be undertaken."

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."

This thesis presents the results of indirect dark matter searches in the gamma-ray sky of the near Universe, as seen by the MAGIC Telescopes. The author has proposed and led the 160 hours long observations of the dwarf spheroidal galaxy Segue 1, which is the deepest survey of any such object by any Cherenkov telescope so far. Furthermore, she developed and completely characterized a new method, dubbed "Full Likelihood", that optimizes the sensitivity of Cherenkov instruments for detection of gamma-ray signals of dark matter origin. Compared to the standard analysis techniques, this novel approach introduces a sensitivity improvement of a factor of two (i.e. it requires 4 times less observation time to achieve the same result). In addition, it allows a straightforward merger of results from different targets and/or detectors. By selecting the optimal observational target and combining its very deep exposure with the Full Likelihood analysis of the acquired data, the author has improved the existing MAGIC bounds to the dark matter properties by more than one order of magnitude. Furthermore, for particles more massive than a few hundred GeV, those are the strongest constraints from dwarf galaxies achieved by any gamma-ray instrument, both ground-based or space-borne alike.

Digital sky surveys, data from orbiting telescopes, and advances in computation have increased the quantity and quality of astronomical data by several orders of magnitude in recent years. Making sense of this wealth of data requires sophisticated statistical and data analytic techniques. Fortunately, statistical methodologies have similarly made great strides in recent years. Powerful synergies thus emerge when astronomers and statisticians join in examining astrostatistical problems and approaches. The volume focuses on several themes: · The increasing power of Bayesian approaches to modeling astronomical data · The growth of enormous databases, leading an emerging federated Virtual Observatory, and their impact on modern astronomical research · Statistical modeling of critical datasets, such as galaxy clustering and fluctuations in the microwave background radiation, leading to a new era of precision cosmology · Methodologies for uncovering clusters and patterns in multivariate data · The characterization of multiscale patterns in imaging and time series data As in earlier volumes in this series, research contributions discussing topics in one field are joined with commentary from scholars in the other. Short contributed papers covering dozens of astrostatistical topics are also included.

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.

This work investigates the theoretical and cosmological implications of modifying Einstein's theory of general relativity. It explores two classes of modifications to gravity: those in which the graviton is given a small mass, and those in which Lorentz invariance is spontaneously broken. It elucidates the nature of cosmological perturbations in theories of massive bimetric gravity, including a potentially deadly instability. Theories of gravity beyond general relativity could explain why the expansion of the Universe is accelerating, obviating the need for a dark energy, and can also affect the evolution of the early Universe. Next, it investigates the nature of spacetime in massive gravity theories that contain two different spacetime metrics. Lastly, the strongest constraints to date are placed on the size of Lorentz-violating effects in the gravity sector during inflation.

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.

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

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.

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.

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."

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.

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.

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.

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.

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."

"If you buy just one guide...you won't do better than this" - BBC Sky at Night Magazine "I will continue to enjoy 'Philip's Stargazing' as the months go by" - Helen Sharman, Astronaut "Very useful indeed" - Chris Lintott, Sky at Night presenter Discover the latest in stargazing with the new and definitive guide to the night sky. Whether you're a seasoned astronomer or just starting out, Philip's Stargazing 2022 is the only book you'll need. Compiled by experts and specially designed for use in Britain and Ireland, Stargazing 2022 acts as a handily illustrated and comprehensive companion. - 12 Brand-New Maps for year-round astronomical discovery - Month-to-Month information. Daily Moon Phase Calendar, highlighting special lunar events throughout the year - Planet Watch for ideal viewing days in 2022 - Avoid light pollution with our detailed Dark Sky Map - Expert advice and insight throughout from internationally renowned Professor Nigel Henbest - A 'Behind the Scenes' look at astrophotography from expert Robin Scagell - Complete calendar of major astronomical events, including the Top 20 Sky Sights of 2022 - Jargon Buster, explaining common or confusing terms - The planets' movements explained from solar and lunar eclipses to meteor showers and comets

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."

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.