On the occasion of the retirement of Ulrich Schwarz, a symposium was held in Groningen in May of 1996, celebrating his contributions to the study of the int- stellar medium, including his work on the high-velocity clouds. The coming together of many specialists in the latter ?eld prompted the idea of compiling a book c- taining their contributions, and summarizing the status of our understanding of the high-velocity cloud phenomenon. This seemed especially worthwhile at the time, since many exciting developments were taking place. After the discovery of some H i clouds with high velocities, about 40 years ago, the subject had been dominated by 21-cm observations of H i emission. Starting in the mid-1980s much progress was being made because of the availability of new instruments, such as large ground-based optical telescopes and UV observatories in space. The connections between the work on high-velocity clouds and other studies of the properties of the (hot) interstellar medium also became clearer.

The paradigm of a dark energy- and dark matter-dominated Universe, with the hierarchical merger scenario for the formation of galaxies, has scored impressive successes in matching the observed Universe. However, the theory fails to explain the difficulty in generating ordinary disk galaxies such as the Milky Way, suggesting that some important physics must be missing in current models. IAU Symposium 254 was organized to address this question, gathering researchers from an unusually broad range of fields, from cosmology to interstellar matter, and the formation and evolution of stars. High-class reviews, lectures and posters combine to define the frontiers in the field and point the way to new avenues of research. This volume presents a unique set of succinct overviews illuminating the full range of topics in this very active field. It also honors Danish astrophysicist Bengt Strömgren (1908-1987), who laid much of the foundation for this entire field.

On the occasion of the retirement of Ulrich Schwarz, a symposium was held in Groningen in May of 1996, celebrating his contributions to the study of the int- stellar medium, including his work on the high-velocity clouds. The coming together of many specialists in the latter ?eld prompted the idea of compiling a book c- taining their contributions, and summarizing the status of our understanding of the high-velocity cloud phenomenon. This seemed especially worthwhile at the time, since many exciting developments were taking place. After the discovery of some H i clouds with high velocities, about 40 years ago, the subject had been dominated by 21-cm observations of H i emission. Starting in the mid-1980s much progress was being made because of the availability of new instruments, such as large ground-based optical telescopes and UV observatories in space. The connections between the work on high-velocity clouds and other studies of the properties of the (hot) interstellar medium also became clearer.

Since the discovery of the cluster soft excess (CSE) over eight years ago, its properties and origin have been the subject of debate. With the recent launch of new missions such as XMM-Newton and FUSE, we are beginning to answer some of the complex issues regarding the phenomenon. This conference proceedings is an attempt to bring together the latest research results and covers both observational and theoretical work on the CSE and related topics. One of the main topics is the possible relationship between the CSE and the warm-hot intergalactic medium (WHIM), which is believed to harbor 50% of the baryons in the near Universe. New data from both XMM-Newton and FUSE have indicated a possible causal link between the WHIM and CSE. Evidence is based on the apparent detection of O VII emission lines in the soft excess spectrum of the outskirts of several clusters, as well as reports of absorption lines at local and higher redshifts (seen in the spectra of distant sources) as signature of the WHIM. However, while there has been considerable optimism in attributing a substantial fraction of the cluster soft excess flux to WHIM emission, other work shows that, for example, the amount of WHIM material predicted by theoretical simulations falls way short of that necessary to account for the CSE. Other work indicates that at the cores of some cluster this excess emission is so strong, it is impossible to invoke the thermal model without at the same time enlisting radically new physics. Thus alternative interpretations involving non-thermal processes are also reported and being pursued in earnest. Whatever the origin of CSE may turn out to be, results in this book show that it has become beyond reasonable doubt that the phenomenon itself is observationally established. This book reports the scientific progress made by bringing together scientists from a wide range of disciplines. It clearly demonstrates the importance of such meetings and participants if we are to solve this puzzle. This volume is aimed at scientists and graduate students in astronomy who want to learn about the latest results on cluster soft excess observations and theoretical implications.

This is volume 5 of Planets, Stars and Stellar Systems, a six-volume compendium of modern astronomical research, covering subjects of key interest to the main fields of contemporary astronomy. This volume on “Galactic Structure and Stellar Populations”, edited by Gerard F. Gilmore, presents accessible review chapters on Stellar Populations, Chemical Abundances as Population Tracers, Metal-Poor Stars and the Chemical Enrichment of the Universe, The Stellar and Sub-Stellar Initial Mass Function of Simple and Composite Populations, The Galactic Nucleus, The Galactic Bulge, Open Clusters and Their Role in the Galaxy, Star Counts and the Nature of Galactic Thick Disk, The Infrared Galaxy, Interstellar PAHs and Dust, Galactic Neutral Hydrogen, High-Velocity Clouds, Magnetic Fields in Galaxies, Astrophysics of Galactic Charged Cosmic Rays, Gamma-Ray Emission of Supernova Remnants and the Origin of Galactic Cosmic Rays, Galactic Distance Scales, Globular Cluster Dynamical Evolution, Dynamics of Disks and Warps, Mass Distribution and Rotation Curve in the Galaxy, Dark Matter in the Galactic Dwarf Spheroidal Satellites, and History of Dark Matter in Galaxies. All chapters of the handbook were written by practicing professionals. They include sufficient background material and references to the current literature to allow readers to learn enough about a specialty within astronomy, astrophysics and cosmology to get started on their own practical research projects. In the spirit of the series Stars and Stellar Systems published by Chicago University Press in the 1960s and 1970s, each chapter of Planets, Stars and Stellar Systems can stand on its own as a fundamental review of its respective sub-discipline, and each volume can be used as a textbook or recommended reference work for advanced undergraduate or postgraduate courses. Advanced students and professional astronomers in their roles as both lecturers and researchers will welcome Planets, Stars and Stellar Systems as a comprehensive and pedagogical reference work on astronomy, astrophysics and cosmology.

The increasing power of computer resources along with great improvements in observational data in recent years have led to some remarkable and rapid advances in astrophysical fluid dynamics. The subject spans three distinct but overlapping communities whose interests focus on (1) accretion discs and high-energy astrophysics; (2) solar, stellar, and galactic magnetic fields; and (3) the geodynamo, planetary magnetic fields, and associated experiments. This book grew out of a special conference sponsored by the London Mathematical Society with the support of EPSRC that brought together leading researchers in all of these areas to exchange ideas and review the status of the field. The many interesting problems addressed in this volume concern:

The gas and dust between the stars emit across the electromagnetic spectrum and are found in a range of physical conditions from diffuse plasmas to cold, dense molecules. Through their study we see how quantum processes shape the structure of our Galaxy and fluid mechanics sets the stellar mass scale. The Interstellar Medium is a very broad subject with layers of complexity, a long history and a steady flow of new results. This comprehensive yet accessible textbook provides a self-contained one-semester course for advanced undergraduate or beginning graduate students. It is written in a style that students can follow by themselves and allows instructors to use class time to go deeper into the details or show applications to current research. It makes extensive use of publicly accessible data to illustrate specific points and to encourage students to learn by performing their own analyses.

Issues in Aerospace and Defense Research and Application: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Aerospace and Defense Research and Application. The editors have built Issues in Aerospace and Defense Research and Application: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Aerospace and Defense Research and Application in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Aerospace and Defense Research and Application: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Dealing with astrophysics derived from the radiation emitted by radioactive atomic nuclei, this book describes the different methods used to measure cosmic radio-isotopes. It demonstrates how this astronomical window has contributed to the understanding of the sources and the chemical evolution of cosmic gas. Reference materials and explanations are included for students in advanced stages of their education. Nuclear reactions in different sites across the universe lead to the production of stable and unstable nuclei. Their abundances can be measured through different methods, allowing to study the various nuclear processes taking place in cosmic environments. Nucleosynthesis is the cosmic formation of new nuclear species, starting from hydrogen and helium resulting from the big bang origins. Stars create and eject synthesized nuclei during their evolution and explosions. Incorporation of the new interstellar composition into next-generation stars characterises the compositional (chemical) evolution of cosmic gas in and between galaxies. Radioactive species have unique messages about how this occurs. Since the first Edition of this book published in 2011 with the title Astronomy with Radioactivities, long-awaited new direct observations of supernova radioactivity have been made and are now addressed in two updated chapters dealing with supernovae. In this second Edition, the advances of recent years beyond one-dimensional treatments of stellar structure and stellar explosions towards 3-dimensional models have been included, and led to significant re-writings in Chapters 3-5. The sections on the Solar System origins have been re-written to account for new insights into the evolution of giant molecular clouds. The chapter on diffuse radioactivities now also includes material measurements of radioactivities in the current solar system, and their interpretations for recent nucleosynthesis activity in our Galaxy. Significant new results on gamma-rays from positron annihilations have been accounted for in that chapter, and led to new links with nucleosynthesis sources as well as interstellar transport processes. A new chapter now provides a description of interstellar processes often called 'chemical evolution', thus linking the creation of new nuclei to their abundance observations in gas and stars. The experimental / instrumental chapters on nuclear reaction measurements, on gamma-ray telescopes, and pre-solar grain laboratories have been updated. Moreover, new windows of astronomy that have been opened up in recent years have been included in the discussions of the multi-messenger approach that broadens the basis for astrophysical insights.