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.

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."

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.

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.

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.

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."

This book presents the proceedings of the IVth Azores International Advanced School in Space Sciences entitled "Asteroseismology and Exoplanets: Listening to the Stars and Searching for New Worlds". The school addressed the topics at the forefront of scientific research being conducted in the fields of asteroseismology and exoplanetary science, two fields of modern astrophysics that share many synergies and resources. These proceedings comprise the contributions from 18 invited lecturers, including both monographic presentations and a number of hands-on tutorials.

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."

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.

ThlS volume contalns a serles of lectures presented at the NATO Advanced Study Instltute on Hlgh Energy Phenomena Around Collapsed Stars, held ln Cargese, CorSlca from September 2 tlll Septemcer 13, 1985. The course was planned ln collaboratlon wlth a SClentlflC Organiz ing Commlttee (C. Cesarsky, France; A. Lyne, U.K.; D. Plnes, USA; J. Trlimper, W. Germany; E. Van den Heuvel, The Netherlands and L. Wolt]er, E.S.O., Mlinlch) and was fully supported by the NATO SClentlflc Affalrs Dlvlsion. It was organized wlth the alm of provldlng students and young researchers with an up-to-date account on the subject of galactlc hlgh energy astrophyslCS and was attended by about 60 researchers from many countrles. The lectures and seminars dld represent a complete coverage of our present knowledge and understandlng of Supernovae, Supernovae Remnants, Pulsars, sources of hlgh energy photons and partlcles. Most of them are reproduced ln thlS volume although unfortunately a few speakers chose not to submlt thelr text Slnce they felt that the materlal was already amply avallable ln the eXlstlng llterature. I wlsh to express my gratltude to the SClentlflc Affalrs Dlvislon of the North Atlantlc Treaty Organlzatlon for the generous support glven to the Instltute and to the lecturers and particlpants who contributed so much to the success of the course."

''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.

The Milky Way Galaxy offers a unique opportunity to study the structure and contents of a major stellar system in three dimensions, at high spatial and spectral resolution, and to very large galactocentric distances. This potential can be realised only by statistical surveys of large areas of the sky, and by detailed study of specific regions with exceptional properties, such as the Galactic centre, and of specific classes of object, such as the globular clusters. The acquisition of such data from a variety of ground-based and satellite surveys has been a primary topic of Galactic research for some years. Several such surveys have been completed recently, and have led to a substantial modification of our understanding of Galactic structure and evolution. The importance of the ability of satellite observatories to survey and to study wavelengths which are inaccessible from the ground is evident in the wealth of data discussed and analysed in this volume which is derived from satellites, specifically COS-B, HEAD-I, HEAO-3, IRAS, PIONEER-lO, SAS-2, and TENMA. The cru cial role of ground-based observations to complement and comprehend the satellite data is also well evident. Similarly, the major ground-based studies whose results are reported here illustrate the necessity for carefully conceived and executed very large scale surveys of many types of object and many parts of parameter space before a coherent picture of the Galaxy will be available."

This book contains the proceedings of the first large IAU Symposium dedicated to the bulges of spiral galaxies. Detailed attention is paid to the bulge of the Milky Way, one of the major building blocks of this system. Topics include the definition of the bulge in our Galaxy and its relation to the so-called spheroid. Discussions are presented regarding the stars contained in this bulge, their astrophysical properties, their motions and the metallicity variations which appear to be present. The possible existence of a bar in the bulge and its origin and future are also examined. The same topics are discussed in less detail for the bulges of other galaxies.

The concept of Stellar Populations has played a fundamental role in astronomy in the last few decades. It was introduced by Walter Baade after he was able to resolve the Andromeda Nebula and its companions into stars when he used red-sensitive plates and realised that there were two fundamentally different Herzsprung-Russell diagrams in our and these nearby galaxies (common stars in the solar neighborhood versus globular clusters). This result was published in two papers in 1944 in volume 100 of the Astrophysical Journal. Subsequent research gave the concept a much firmer basis and at the famous Vatican Symposium of 1957 resulted in a general scheme of the concept and a working hypothesis for idea's on the formation and evolution of the Galaxy. This has been a guiding principle of studies of our and other galaxies for decades. Some years ago it seemed to us appropriate to commemorate Baade's seminal work in 1994, when it would have its 50-th anniversary, and to review its present status and also its role in contempory understanding. While we were in Leiden for an administrative committee, we discussed the matter again and over beers on October 29, 1991 we decided the take the initiative for an IAU Symposium on the subject during the 1994 IAU General Assembly in Den Haag, the Netherlands.

This thesis presents a study of the origin of an apparently extended X-ray emission associated with the Galactic ridge. The study was carried out with broadband spectra obtained from mapping observations in the Galactic bulge region conducted in 2005-2010 by the Suzaku space X-ray observatory. The spectra were analyzed with a newly constructed X-ray spectral model of an accreting white dwarf binary that is one of the proposed candidate stars for the origin of the Galactic ridge emission in the higher energy band. Fitting of the observed Galactic ridge spectra with the model showed that there is another spectral component that fills the gap between the observed X-ray flux and the component expected from the accreting white dwarf spectral model in the lower energy band. This additional soft spectral component was nicely explained by an X-ray spectral model of normal stars. The result, together with previously reported high-resolution imaging results, strongly supports the idea that the Galactic ridge X-ray emission is an assembly of dim, discrete X-ray point sources.

This volume reviews the current status with respect to both theory and observation of the extragalactic distance scale. A sufficient accuracy is required both for a precise determination of the cosmological parameters and also in order to achieve a better understanding of physical processes in extragalactic systems. The "standard candles," used to set up the extragalactic distance scale, reviewed in this book include cepheid variables, RR Lyrae variables, novae, Type Ia and Type II supernovae as well as globular clusters and planetary nebulae.