This book was first published in 2007. Variable stars are those that change brightness. Their variability may be due to geometric processes such as rotation, or eclipse by a companion star, or physical processes such as vibration, flares, or cataclysmic explosions. In each case, variable stars provide unique information about the properties of stars, and the processes that go on within them. This book provides a concise overview of variable stars, including a historical perspective, an introduction to stars in general, the techniques for discovering and studying variable stars, and a description of the main types of variable stars. It ends with short reflections about the connection between the study of variable stars, and research, education, amateur astronomy, and public interest in astronomy. This book is intended for anyone with some background knowledge of astronomy, but is especially suitable for undergraduate students and experienced amateur astronomers who can contribute to our understanding of these important stars.

Supernovae and gamma-ray bursts are the strongest explosions in the Universe. Observations show that, rather than being symmetrical, they are driven by strong jets of energy and other asymmetrical effects. These observations demand theories and computations that challenge the biggest computers. This volume marks the transition to a fresh paradigm in the study of stellar explosions. It highlights the burgeoning era of routine supernova polarimetry and the insights into core collapse and thermonuclear explosions. With chapters by leading scientists, the book summarises the status of a fresh perspective on stellar explosions and should be a valuable resource for graduate students and research scientists.

Galaxy groups and clusters provide excellent laboratories for studying galaxy properties in different environments and at different look-back times. In particular, the recent detections of high-redshift cluster candidates, only possible with the current high-technology instrumentation, add a new dimension to the problem. Along with the ever increasing computing power and sophisticated algorithms to model clusters of galaxies, it may help us to understand the origins of today's groups and clusters, as well as of their member galaxies. These workshop proceedings provide a snapshot of the current research in this subject, covering the observations, theory and numerical simulations relevant to galaxy evolution in groups and clusters. In this book, intended primarily to researchers in the field, particular emphasis is given to the recent impressive progress in the field, on important new results, and on the future prospects and open questions to be tackled.

Starburst regions in nearby and distant galaxies have a profound impact on our understanding of the early universe. This new, substantially updated and extended edition of Norbert Schulz's unique book "From Dust to Stars" describes complex physical processes involved in the creation and early evolution of stars. It illustrates how these processes reveal themselves from radio wavelengths to high energy X-rays and gamma-rays, with special reference towards high energy signatures. Several sections devoted to key analysis techniques demonstrate how modern research in this field is pursued and new chapters are introduced on massive star formation, proto-planetary disks and observations of young exoplanets. Recent advances and contemporary research on the theory of star formation are explained, as are new observations, specifically from the three great observatories of the Spitzer Space Telescope, the Hubble Space Telescope and the Chandra X-Ray Observatory which all now operate at the same time and make high resolution space based observing in its prime. As indicated by the new title two new chapters have been included on proto-planetary disks and young exoplanets. Many more colour images illustrate attractive old and new topics that have evolved in recent years. The author gives updates in theory, fragmentation, dust, and circumstellar disks and emphasizes and strengthens the targeting of graduate students and young researchers, focusing more on computational approaches in this edition.

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."

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.

Based on a number of new discoveries resulting from 10 years of Chandra and XMM-Newton observations and corresponding theoretical works, this is the first book to address significant progress in the research of the Hot Interstellar Matter in Elliptical Galaxies. A fundamental understanding of the physical properties of the hot ISM in elliptical galaxies is critical, because they are directly related to the formation and evolution of elliptical galaxies via star formation episodes, environmental effects such as stripping, infall, and mergers, and the growth of super-massive black holes. Thanks to the outstanding spatial resolution of Chandra and the large collecting area of XMM-Newton, various fine structures of the hot gas have been imaged in detail and key physical quantities have been accurately measured, allowing theoretical interpretations/predictions to be compared and tested against observational results. This book will bring all readers up-to-date on this essential field of research.

This volume is the proceedings of the IAU Symposium "Star Clusters." It includes the invited papers, brief accounts of the contributed papers, and the associated discussion. The topics discussed at the symposium included many aspects of recent research on open clusters and globular clusters. Because cluster studies touch on so many areas of stellar, galactic and extragalactic astronomy, this volume should be of interest to a wide astronomical readership. In setting up the scientific program for this symposium, the scientific organizers were mindful of a very successful NATO Advanced Study Institute at Cambridge (UK) in August, 1978, at which recent advances in globular cluster studies were thoroughly reviewed. So the emphasis at this symposium was on open clusters and problems common to open and globular clusters. One day only was scheduled exclusively for globular clusters, and the topics chosen for that day are ones in which rapid progress is being made. We would like to mention here two aspects of this symposium which contributed significantly to the useful and relaxed discussion following the scientific contributions.

More than a decade has passed since pulsars were discovered at Cambridge by J. Bell and A. Hewish. The past 13 years have seen ex tensive and at first rather hectic research, and a considerable amount of observational and theoretical knowledge has been accumulated. Looking back over one decade of pulsar research, it seems worth while to ask what the real impact of the detection was and if our view of the universe has changed as a result of this discovery. The excite ment of the first months and years has ebbed down considerably, with the result that pulsar research has become the task of a few scientists, working in small groups, scattered over many countries. As more and more knowledge was acquired, pulsars changed eventually from the bizarre pUlsing objects -- as they were considered in the beginning -- to more normal stars of astrophysical interest. Still, pulsars are the manifestation of matter in its most extreme form -- neutron star matter -- for which an equivalent can be found on earth only in the very nucleus of an atom. Neutron stars were predicted quite early in the history of modern astrophysics, and although many of their features were already known from theoretical studies, astro physicists were not sure if we had the slightest chance to actually "see" these objects. It therefore took some time after the historical detection paper of Hewish and coworkers before astronomers became con vinced that pulsars were neutron stars."

ThisvolumeisacollectionofarticlesoriginallypublishedonaSpecialIssueoftheAstrophysicsandSpaceScienceJournal. It is intended to give a comprehensive overview of the current state of knowledge in solar and stellar modelling, with the aim of comparing and extending what we know from the detailed solar modelling, made possible by the helioseismic tools and by the recent analysis of the solar spectrum, to the modelling and understanding of generic stellar structures and their evolution. Particular emphasis is devoted to the role of the input physics, and its relevant uncertainties, in the construction of stellar models and in the resulting predictions for general observable quantities. Issues related to convection, overshoot, diffusion and settling of helium and heavy elements, rotation, chemical composition and magnetic eld are extensively discussed. Large space is dedicated to the application of helio- and asteroseismic techniques as tools to prove the theory of the evolution and the structure of the stars. Comments on prospects for future improvements and re nements of the theoretical models are given, focusing on the possibility of getting ever more precise helioseismic and asteroseismic observations from ground and space. The articles included in this volume are the results of the HELAS-NA5 workshop 'Synergies between solar and stellar modelling' held in Rome from 22nd to 26th of June 2009, which was an unique occasion to gather the solar and the stellar physics communities to discuss the urgent questions risen by recent photometric and spectroscopic observational results.

Is the current state of our Galaxy primarily the result of its initial conditions or is it the product of a lifetime of complex interactions with its environment? Gathered in this volume are papers presented at an international meeting in Granada, Spain, dedicated to exploring this fundamental question. This review examines all the key physical processes involved in the formation and evolution of the Milky Way. A dozen invited review articles by international experts summarise our understanding to date; whilst more than seventy topical research papers present the latest results. Together, these papers provide a view on topical issues such as disk instabilities, large-scale star formation, large-scale structure formation in our Galaxy, chemical evolution, Disk-Halo feedback, the galactic globular cluster system, stellar populations, and the formation of galaxies. Also included are three panel sessions identifying key routes for critical future research.

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.

Starburst regions in nearby and distant galaxies have a profound impact on our understanding of the early universe. This new, substantially updated and extended edition of Norbert Schulz s unique book "From Dust to Stars" describes complex physical processes involved in the creation and early evolution of stars. It illustrates how these processes reveal themselves from radio wavelengths to high energy X-rays and gamma rays, with special reference towards high energy signatures. Several sections devoted to key analysis techniques demonstrate how modern research in this field is pursued and new chapters are introduced on massive star formation, proto-planetary disks and observations of young exoplanets. Recent advances and contemporary research on the theory of star formation are explained, as are new observations, specifically from the three great observatories of the Spitzer Space Telescope, the Hubble Space Telescope and the Chandra X-Ray Observatory which all now operate at the same time and make high resolution space based observing in its prime. As indicated by the new title two newchapters have been included on proto-planetary disks and young exoplanets. Many more colour images illustrate attractive old and new topics that have evolved in recent years. The author gives updates in theory, fragmentation, dust, and circumstellar disks and emphasizes and strengthens the targeting of graduate students and young researchers, focusing more on computational approaches in this edition."

X-ray astronomy is the prime available window on astrophysical compact objects: black holes, neutron stars and white dwarfs. New observational opportunities have led to an explosion of knowledge in this field. This book provides a comprehensive overview of the astrophysics of compact objects that emit X-rays. Sixteen chapters written by the foremost experts in the field cover the observations and the astrophysical interpretation of these objects. Topics covered include binary systems, gamma ray burst sources, anomalous X-ray pulsars, super-soft sources, and enigmatic fast X-ray transients. Further chapters are dedicated to isolated neutron stars and the X-ray source populations of globular clusters. The properties of X-ray binaries are discussed in depth in chapters on quasi-periodic oscillations and related aperiodic X-ray variability, X-ray bursts, black holes, and relativistic jets. This is a valuable reference for both graduate students and active researchers.

Over the past 200 years, our knowledge of stars has expanded enormously. From seeing myriad dots of different brightnesses, we haved moved on to measure their distances, temperatures, sizes, chemical compositions, and even ages, finding both young and ancient stars that dwarf our Sun and are dwarfed by it. Unique in its approach, Extreme Stars describes the lives of stars from a new perspective by examining their amazing features. The result is a refreshing, up-to-date, and engaging overview of stellar evolution, suitable for everyone interested in viewing or studying the stars. Ten chapters, generously illustrated throughout, explain the natures of the brightest, the largest, the hottest, and the youngest, among other kinds of stars, ending with a selection of the strangest stars the Universe has to offer. Extreme Stars shows how stars develop and die and how each extreme turns into another under the inexorable twin forces of time and gravity. James B. Kaler is Professor of Astronomy at the University of Illinois, Champaign-Urbana. He has held Fulbright and Guggenheim Fellowships, has been awarded medals for his work from the University of Liege in Belgium and the University of Mexico, and most recently was selected to give the Armand Spitz lecture by the Great Lakes Planetarium Association. His research area, in which he has published over 100 papers, involves dying stars. Kaler has also written for a variety of popular magazines, including Astronomy, Sky & Telescope, and Scientific American. His previous books include The Ever-Changing Sky (Cambridge, 1996), Stars and their Spectra (Cambridge, 1997), Cosmic Clouds (Scientific American Library Paperback, 1998), and The Little Book of Stars (Copernicus, 2000). He is a current member of the Board of Directors of the Astronomical Society of the Pacific and is a frequent guest on radio and television shows.

A conference on Observational Evidence for Black Holes in the Universe' was held in Calcutta during January 10-17, 1998. This was the first time that experts had gathered to debate and discuss topics such as: Should black holes exist? If so, how to detect them? Have we found them? This book is the essence of this gathering. Black holes are enigmatic objects since it is impossible to locate them through direct observations. State-of-the-art theoretical works and numerical simulations have given us enough clues of what to look for. Observations, from both ground and space-based missions, have been able to find these tell-tale signatures. This book is a compendium of our present knowledge about these theories and observations. Combined, they give a thorough idea of whether black holes, galactic as well as extragalactic, have been detected or not. Forty-one experts of the subject have contributed to this volume to make it the most comprehensive to date.

This up-to-date review of the basic elements directly connected to the evolution of galaxies links data about remote galaxies to the observation of very old populations in our own galaxy. Young researchers and well-known specialists discuss the difficulties and remaining uncertainties of the problem.

A geologist and fellow of the Royal Astronomical Society, Isaac Roberts (1829-1904) made significant contributions to the photography of star-clusters and nebulae. By championing reflecting rather than refracting telescopes, Roberts was able to perceive previously unnoticed star-clusters, and was the first person to identify the spiral shape of the Great Andromeda Nebula. Roberts' use of a telescope for photographing stars, and a long exposure time, provided greater definition of stellar phenomena than previously used hand-drawings. Although Roberts' conclusions about the nature of the nebulae he photographed were not always correct, the book is significant for the possibilities it suggests for nebular photography. Published in 1893 and 1899, the two-volume Photographs of Stars represents the summation of his work with his assistant W. S. Franks at his observatory in Crowborough, Sussex. Volume 2 contains 29 plates of stars, and his conclusions about their origins and nature.

A geologist and fellow of the Royal Astronomical Society, Isaac Roberts (1829 1904) made significant contributions to the photography of star-clusters and nebulae. By championing reflecting rather than refracting telescopes, Roberts was able to perceive previously unnoticed star-clusters, and was the first to identify the spiral shape of the Great Andromeda Nebula. Roberts' use of a telescope for photographing stars, and a long exposure time, provided greater definition of stellar phenomena than previously used hand-drawings. Although Roberts' conclusions about the nature of the nebulae he photographed were not always correct, the book is significant for the possibilities it suggests for nebular photography. Published in London in 1893 and 1899, the two-volume Photographs of Stars represents the summation of his work with his assistant W. S. Franks at his observatory in Crowborough, Sussex. Volume 1 contains 51 collotype plates of stars, and descriptions of his instruments and methods.

During the past decade, convincing evidence has been accumulated concerning the effect of active galactic nuclei (AGN) activity on the internal and external environment of their host galaxies. Featuring contributions from well-respected researchers in the field, and bringing together work by specialists in both galaxy formation and AGN, this volume addresses a number of key questions about AGN feedback in the context of galaxy formation. The topics covered include downsizing and star-formation time scales in massive elliptical galaxies, the connection between the epochs of supermassive black hole growth and galaxy formation and the question of whether AGN and star formation coexist. Authors also discuss key challenging computational problems, including jet-interstellar/intergalactic medium interactions, and both jet- and merging-induced star formation. Suitable for researchers and graduate students in astrophysics, this volume reflects the engaging and lively discussions taking place in this emerging field of research.

Astrometry from space was performed for the first time and with great success by the ESA Hipparcos satellite (1989-93). This mission was designed as an as trometry mission, but the use of a photon counting detector made it possible to produce very important photometric results: the most accurate astronomical pho tometry ever by the main Hipparcos mission in a very broad band of 120000 stars, and the two-colour Tycho-2 photometry of 2.5 million stars. The cornerstone ESA mission GAIA was approved in October 2000 for launch not later than 2012. This mission will use CCDs in time-delayed integration mode instead of the photo-cathode detectors used in Hipparcos. Due to the higher quantum efficiency of the CCDs, simultaneous integration of many stars, and larger tele scope apertures GAIA will utilize the star light a million times more efficiently than Hipparcos, resulting in astrometry and multi-colour photometry for one billion stars. GAIA photometry is crucial for the scientific utilization of the astrometric results, and the photometric data have a high scientific content in themselves.

On August 2000 in the Lomonosov Moscow State University the first scientific conference dedicated to chaos in the real astronomical systems was held. The most prominent astrophysisists - specialist in the field of stochastic dynamics - attended the conference. A broad scope of the problems related to the observed manifes tations of chaotic motions in galactic and stellar objects, with the involvement of basic theory and numerical modeling, were addressed. The idea (not so obvious, as we believe, to many astrophysicists) was to show that, while great progress in the field of stochastic mechanics was accomplished, the science of chaos in actually observed systems is only just being born. Basically, the situation described prompted the organizers to hold the meeting in order to discuss chaotic processes in real systems. It seemed worthwhile to begin these introductory remarks with a brief descrip tion of some events that preceeded the conference. Since actually existing systems are the subject of the natural sciences, and in the latter experiments play the key role, we shall begin our account with the experimental results."

When Edwin Dunkin (1821 1898) published this book in 1869, it was received with widespread acclaim by both professional astronomers and the reading public. Dunkin, a distinguished astronomer who published widely in academic journals and later served in the prestigious roles of Deputy Astronomer Royal (1881 1884) and President of the Royal Astronomical Society (1880), is still best known for this work of popular astronomy that has functioned as an indispensable tool for generations of amateurs. Chapter 1 derives from Dunkin's famous 'The Midnight Sky at London' articles, previously published in Leisure Hour, which describe the London midnight sky during each month of the year. Other chapters cover the Southern Hemisphere, the constellations, the properties of fixed stars, the solar system, and meteors and shooting stars. The volume is well illustrated with star maps and engravings. It is a classic work of popular nineteenth-century astronomical writing.

Admiral William Henry Smyth's Sidereal Chromatics (1864) represents a landmark achievement in nineteenth-century astronomy, offering the most precise observations of the colours of double stars yet recorded. An expansion upon his well-known Bedford Cycle of Celestial Objects, which garnered a gold medal from the Royal Astronomical Society, Sidereal Chromatics provides both a theory concerning the source of double-star colours and a method for determining their most exact description. Detailed charts compare Smyth's measurements of more than one hundred double stars with his own previously published observations and those of his fellow astronomer, Father Benedetto Sestini. This edition also includes Smyth's famous colour chart, an attempt to standardise the process of identifying double-star colours. Sidereal Chromatics ends with Smyth's plea to amateur astronomers to continue the effort of charting the heavens, aided by improved telescopes and works such as his, 'trustworthy treatises available to all men'.

Observational cosmology, with the help of large telescopes, combined with the capabilities of the Hubble Space Telescope and other space missions, allow astronomers to directly observe galaxy assembly over cosmic time. These developments demand that scientists are trained in the methods suited to the study of distant galaxies. This volume contains the lectures delivered at the XI Canary Islands Winter School of Astrophysics, reviewing both scientific results and the main questions in the field. It covers the study of normal galaxies, distant galaxies, and studies based on far-infrared diagnostics, it reviews quasar absorption lines, and the properties of nearby galaxies. Each chapter is written by a world expert in the field, making the book an essential reference for all astronomers working in the field of high-redshift galaxies.