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Books > Science & Mathematics > Physics > Applied physics & special topics > Astrophysics
Adaptive optics allows the theoretical limit of angular resolution to be achieved from a large telescope, despite the presence of turbulence. Thus an eight meter class telescope, such as one of the four in the Very Large Telescope operated by ESO in Chile, will in future be routinely capable of an angular resolution of almost 0.01 arcsec, compared tot he present resolution of about 0.5 arcsec for conventional imaging in good condition. All the world's major telescopes either have adaptive optics or are in the process of building AO systems. It turns out that a reasonable fraction of the sky can be observed using adaptive optics, with moderately good imaging quality, provided imaging in done in the near IR. To move out of the near IR, with its relatively poor angular resolution, astronomers need a laser guide star. There is a layer of Na atoms at approximately 90 km altitude that can be excited by a laser to produce such a source, or Rayleigh scattering can be employed lower in the atmosphere. But the production and use of laser guide stars is not trivial, and the key issues determining their successful implementation are discussed here, including the physics of the Na atom, the cone effect, tilt determination, sky coverage, and numerous potential astronomical applications.
The original work presented in this thesis constitutes an important contribution to modern Cosmic Ray (CR) physics, and comes during one of the most exciting periods of this field. The first part introduces a new numerical code (DRAGON) to model the CR propagation in our Galaxy. The code is then used to perform a combined analysis of CR data, making it possible to determine their propagation properties with unprecedented accuracy. The second part is dedicated to a theoretical interpretation of the recent crucial experimental results on cosmic electron and positron spectra (PAMELA, Fermi-LAT experiments). Using the tools developed in the first part of the thesis, the author convincingly argues for the existence of a new spectral component, which could arise either from local astrophysical sources, such as pulsars, or from Dark Matter annihilation or decay. This thesis is a highly advanced work; the methods, analysis and results are clearly and carefully presented. This work is set to become an important reference document for any future work in this area.
Edith Alicia M ller (1918-1995) was the IAU General Secretary from 1976 to 1979, the first woman to have this responsibility. Many friends, students and colleagues, and others who have met Edith at different occasions, give in this book their memories of her. Her fundamental work in solar physics concerned the chemical composition of the Sun, the time variation of its infra-red spectrum, and its thermal structure. Her interests were, however, far broader than that. She was heavily involved in international work for the teaching of astronomy and for the exchange program of young astronomers.
Black Holes are still considered to be among the most mysterious and fascinating objects in our universe. Awaiting the era of gravitational astronomy, much progress in theoretical modeling and understanding of classical and quantum black holes has already been achieved. The present volume serves as a tutorial, high-level guided tour through the black-hole landscape: information paradox and blackhole thermodynamics, numerical simulations of black-hole formation and collisions, braneworld scenarios and stability of black holes with respect to perturbations are treated in great detail, as is their possible occurrence at the LHC. An outgrowth of a topical and tutorial summer school, this extensive set of carefully edited notes has been set up with the aim of constituting an advanced-level, multi-authored textbook which meets the needs of both postgraduate students and young researchers in the fields of modern cosmology, astrophysics and (quantum) field theory.
A quantitative measure of the accuracy of the rate coefficients and the excess energies is a desirable goal of this analysis. There are two major sources of uncertainties: The atomic and molecular data and the solar irradiance. The cross sections and branching ratios used in this analysis come from many different sources; many of them without any error indications. For this reason, we must confine ourselves to a qualitative indication of the reliability of the results. Specifically we give a quality scale in Table II for the data of each mother molecule; A indicating the highest quality of atomic and molecular data and F the lowest quality. The letter B typically means that the threshold is uncertain. For most molecules the cross section at threshold is very small and the rate coefficient for these molecules is therefore not influenced by this uncertainty. For atomic species the cross section is usually large near threshold, but for these species the threshold is known quite accurately. The letter B, therefore, indicates that the rate coefficient is most likely quite accurate, but the excess energy is less accurately known. The letter C usually means that the branching ratios are not well known. This means that the total rate coefficient is very good, but the rate coefficients and the excess energies for the individual branches are less accurate.
The present set of lectures is devoted to magnetohydrodynamic turbulence in astrophysics with strong emphasis on numerical simulations. The book strives for a balance between state-of-the-art reports and a tutorial approach. It is thus particularly suited as an introduction to the field for nonspecialist researchers and postgraduate students, while experienced scientists will find the book to be a comprehensive source of reference for their research.
In the context of the NASA Deep Impact space mission, comet 9P/Tempel1 has been at the focus of an unprecedented worldwide long-term multi-wavelength observation campaign. The comet was also studied throughout its perihelion passage by various sources including the Deep Impact mission itself, the Hubble Space Telescope, Spitzer, Rosetta, XMM and all major ground-based observatories in a wavelength band from cm-wave radio astronomy to x-rays. This book includes the proceedings of a meeting that brought together an audience of theoreticians and observers - across the electromagnetic spectrum and from different sites and projects - to make full use of the massive ground-based observing data set. The coherent presentation of all data sets illustrates and examines the various observational constraints on modelling the cometary nucleus, cometary gas, cometary plasma, cometary dust, and the comet's surface and its activity.
What do combustion engines, fusion reactors, weather forecast, ocean ?ows, our sun, and stellar explosions in outer space have in common? Of course, the physics and the length and time scales are vastly di?erent in all cases, but it is alsowellknownthatinallofthem,onsomerelevantlengthscales,thematerial ?ows that govern the dynamical and/or secular evolution of the systems are chaotic and often unpredictable: they are said to be turbulent. In fact, the term "turbulence" is used for an enormous variety of p- nomena in very di?erent ?elds, including geophysics, astrophysics, and - gineering. Unfortunately, these communities do not talk to each other too often. Therefore, back in 2005, we organized a workshop on "Interdis- plinary Aspects of Turbulence" at the Ringberg Castle in the Bavarian Alps, to discuss topics such as the basic concepts of turbulence, the di?- ent approaches of modelling and simulations used in the various areas, and also possible tests. This workshop was a great success and the proceedings can be found on the Internet (www.mpa-garching.mpg.de/mpa/publications/ proceedings/proceedings-en.html) as well as pdf-?les of several of the talks presented (www.mpa-garching. mpg.de/hydro/Turbulence/).
It is only since recent years that the importance of the effects of outdoor lighting on the night-time environment and on the physical and mental health of humans is recognized on a wider scale. The related issue of light pollution is a particularly complex one, with potential conflicts of interest between the utilities, environmentalists, astronomers, the lighting industry and various government departments. Energy politics are always a sensitive issue, and light pollution is no exception to this rule. The effects of light pollution on flora, fauna -including humans and their widely varying night-time activities- are often subtle and need extensive field studies to be quantified in a sensible manner. The present conference, initiated by Commission 50 of the International Astronomical Union, is an attempt to bring together the astronomical community, the lighting industry, end-users, the utilities, and public authorities for a discussion and an exchange of ideas and information that will create goodwill among these groups and will thus contribute to making the global efforts to reduce pollution more efficient and effective. Radio frequency pollution was also discussed in the context of
radio astronomy and its efforts to create radio-quiet zones in
collaboration with the government authorities that allocate
frequency bands to the various users -mainly the telecommunications
industry- and to protect the major planned and present radio
observatories of the world. Some of the highlights were: Related topics in the book are light pollution education, aircraft contrails, space advertising (with an added document provided by the relevant UN commission), and an experiment on involving the population of an entire country in measuring sky brightness, by using the internet and the media. The text is aimed at professionals from a wide range of disciplines related to lighting and its effects on the night-time environment in the broadest sense of the word. Lay persons interested in this emerging multi-disciplinary field can also find much of interest in this book.
This volume documents the contributions presented at the III Scientific Meeting of the Spanish Astronomical Society (SEA). Covering a wide range of topics, the 92 contributed papers give a comprehensive overview of the current state of Spanish astronomy. The Proceedings include special reviews dealing with the cosmological evolution of star-forming galaxies, the nature of cosmic gamma-ray bursts, infrared astrophysics with ISO, and the distance scale after Hipparcos, with special emphasis on the development of the next generation of instruments to propel astrophysical research into the new century. The contents of these Proceedings thus reflect the broad interests of the Spanish astronomical community. The significance of these proceedings can hardly be exaggerated, since here, for the first time, the SEA publishes the proceedings of its own scientific meeting. The intended audience is professional astronomers and graduate astronomy students worldwide.
Many of the ISO observers who assembled for this workshop at Ringberg c- tle met for the third time in the Bavarian Alps. At two previous meetings in 1989 and 1990 surveys were only a minor topic. At that time we were excited by the discoveries of the IRAS survey mission and wanted to follow it up with pointed observations using an observatory telescope equipped with versatile instruments. With the rapid development of detector arrays and stimulated by ISO's Observing Time Allocation Committee, however, surveys eventually became an issue for the upcoming mission. In a review paper on "Infrared S- veys - the Golden Age of Exploration" given at an IAU meeting in 1996, Chas Beichman already mentioned that there are ISO surveys. They were at the bottom of his hit list, while the winners were future space missions (Planck, SIRTF, etc. ) and ground-based surveys in preparation (Sloan, 2MASS, DE- NIS, etc. ). He organized his table according to the relative explorable volume, calculated from the solid angle covered on the sky and the maximum distance derived from the detection sensitivity. Clearly, with this ?gure of merit, ISO, as a pointed observatory, is rated low. Applying the classical de?nition of a survey, i. e. to search in as large a volume as possible for new or rare objects and/or study large numbers of objects of various classes in order to obtain statistical properties, ISO was indeed limited.
This review of the most up-to-date observational and theoretical information concerning the chemical evolution of the Milky Way compares the abundances derived from field stars and clusters, giving information on the abundances and dynamics of gas.
The accretion process is thought to play a key role in the Universe. This book explains, in a form intelligible to graduate students, its relation to the formation of new stars, to the energy release in compact objects and to the formation of black holes. The monograph describes how accretion processes are related to the presence of jets in stellar objects and active galactic nuclei and to jet formation. The authors treat theoretical work as well as current observational facts. This volume of the highly esteemed Les Houches series is meant as an advanced text that can serve to attract students to exciting new research work in astrophysics.
In this book the author extends the concepts previously introduced in his "Quantum Field Theory in Condensed Matter Physics" to situations in which the strong electronic correlations are crucial for the understanding of the observed phenomena. Starting from a model field theory to illustrate the basic ideas, more complex systems are analysed in turn. A special chapter is devoted to the description of antiferromagnets, doped Mott insulators and quantum Hall liquids from the point of view of gauge theory. This advanced text is written for graduate students and researchers working in related areas of physics.
We stand at the threshold of an exciting era of Asteroseismology. In a few months' time, the Canadian small-satellite asteroseismology mission MOST will be laun ched. Danish and French missions MONS and COROT should follow, with the ESA mission Eddington following in 2007/8. Helioseismology has proved spec tacularly successful in imaging the internal structure and dynamics of the Sun and probing the physics of the solar interior. Ground-based observations have detected solar-like oscillations on alpha Centauri A and other Sun-like stars, and diagnostics similar to those used in helioseismology are now being used to test and constrain the physics and evolutionary state of these stars. Multi-mode oscillations are being observed in an abundance of other stars, including slowly pulsating B stars (SPB stars), delta Scuti stars, Ap stars and the pulsating white dwarfs. New classes of pulsators continue to be discovered across the Hertzsprung-Russell diagram. For good reason it was decided to entitle our conference 'Asteroseismology Across the HR Diagram' . Yet the challenges still to be faced to make asteroseismology across the HR diagram a reality are formidable. Observation, data analysis and theory all pose hard problems to be overcome. In conceiving this meeting, the aim of the organisers was to facilitate a cross-fertilization of ideas and approaches between researchers working on different pulsators and with different areas of expertise. We venture to suggest that in this the conference was a great success."
Gravitational waves were predicted by Einstein over 75 years ago, but have not yet been seen. This book is about the technology of the new generation of interferometric gravitational wave detectors now being built, such as the LIGO (Laser Interferometric Gravitational-Wave Observatory) project in the US. The book aims to make plain how these detectors function, and why it is reasonable to think that gravitational waves may be successfully detected in the next decade.After an introduction to the physical and astronomical aspects of gravitational waves, the book concentrates on explaining the basic principles behind the detectors and discusses the strategies for utilising them. All the required background in astronomy, optics and experimental physics techniques is developed within the text, and anyone with an undergraduate knowledge of physics will be able to follow the arguments presented. The book will be of use not just to physicists and astronomers who wish to acquaint themselves with the subject, but will also prove useful for courses in experimental physics at the advanced undergraduate and graduate levels.
Dramatic progress is a trademark of the recent study of globular cluster systems. Considerations about the formation and evolution compose the first chapter, followed by a chapter on young star clusters. Then come four chapters reviewing the globular cluster system of early-type, late-type and dwarf galaxies, as well as of groups of galaxies. One chapter is dedicated to stellar population models and their applications to the field. Finally a chapter reviews the kinematics of galaxies derived from globular cluster systems and another their role in the context of galaxy formation and evolution studies. As a whole, the book gives an up-to-date view of the field at the beginning of the new decade, which will without doubt again bring significant progress in our understanding of globular cluster systems and galaxy formation and evolution.
This book is one result from the 1996 Millimeter-wave Summer School held at the Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Tonantz- intla, Puebla, Mexico. In collaboration with the University of Massachusetts, INAOE has embarked upon the ambitious project of building the world's largest filled aperture millimeter-wave telescope - the Large Millimeter-wave Tele- scope (LMT), or Gran Telescopio Milimetrico (GTM). The LMT is currently the largest scientific project in Mexico. The summer school had a dual purpose; first, to introduce the Mexican as- tronomical and physics communities to millimeter wavelength astronomy, and second, to provide a forum for a review of several important aspects of the state of the art in observations, theory, interpretation, and technology relevant to this branch of astronomy. The summer school had 18 invited speakers and 44 par- ticipants. The scientific organizing committee (SOC) consisted of Luis Carrasco (UNAM/INAOE, Mexico), Paul Goldsmith (NAIC, Cornell Univ., USA), and Andy Harris (Univ. of Maryland, USA). Members of the local organizing com- mittee (LOC) were Alberto Carramiiiana (INAOE), Emmanuel Mendez Palma (INAOE), Mari Paz Miralles (Harvard-Smithsonian Center for Astrophysics, USA), and William Wall (INAOE).
This book gives an exposition of both the old and new results of spin and torsion effects on gravitational interactions with implications for particle physics, cosmology etc. Physical aspects are stressed and measurable effects in relation to other areas of physics are discussed.Among the topics discussed are: alternative ways of unifying gravity with electroweak and strong interactions by an energy dependent spin torsion coupling constant; the idea that all interactions can be understood as originating from spin curvature coupling; the possibility of cosmological models with torsion providing a solution to the cosmological constant problem; and a demonstration that torsion can lead directly to the quantization of space-time itself.
Galaxies and Chaos examines the application of tools developed for Nonlinear Dynamical Systems to Galactic Dynamics and Galaxy Formation, as well as to related issues in Celestial Mechanics. The contributions collected in this volume have emerged from selected presentations at a workshop on this topic and key chapters have been suitably expanded in order to be accessible to nonspecialist researchers and postgraduate students wishing to enter this exciting field of research.
Magnetic fields are responsible for much of the variability and structuring in the universe, but only on the Sun can the basic magnetic field related processes be explored in detail. While several excellent textbooks have established a diagnostic foundation for exploring the physics of unmagnetized stellar atmospheres through spectral analysis, no corresponding treatise for magnetized stellar atmospheres has been available. The present monograph fills this gap. The theoretical foundation for the diagnostics of stellar magnetism is developed from first principles in a comprehensive way, both within the frameworks of classical physics and quantum field theory, together with a presentation of the various solar applications. This textbook can serve as an introduction to solar and stellar magnetism for astronomers and physicists at the graduate or advanced undergraduate level and will also become a resource book for more senior scientists with a general interest in cosmic magnetic fields.
Some twenty-three years after the discovery of pulsars and their identification as rotating neutron stars, neutron star physics may be regarded as comingofage. Pul sars and accreting neutron stars have now been studied at every wavelength, from the initial radio observations, through optical, X-, and "{-ray, up to the very recent observations in the TeV region, while theorists have studied in some detail relevant physical processes both outside and inside neutron stars. As a result, comparisonof theory with observation provides a test ofour theoretical ideas in fields as diverse as neutron and nuclear matter, superfluidity and superconductivity, the acceleration of high energy particles, and the generation and maintenance of intense magnetic fields. For example, through observations of glitches and post glitch behavior of pulsars, it has become possible to establish the presence ofsuperfluid neutron mat ter in the inner crust of neutron stars, and to determine some of its properties, while neutron stars in compact binary systems offer one ofthe most efficient energy generation mechanisms known. It is in fact the interactive interpretation of these, diverse pieces of information that can lead to major advances in our understanding of the physics of these exotic objects, and justifies the characterization of neutron stars as hadron physics laboratories."
This textbook presents the established sciences of optical, infrared, and radio astronomy as distinct research areas, focusing on the science targets and the constraints that they place on instrumentation in the different domains. It aims to bridge the gap between specialized books and practical texts, presenting the state of the art in different techniques. For each type of astronomy, the discussion proceeds from the orders of magnitude for observable quantities that drive the building of instrumentation and the development of advanced techniques. The specific telescopes and detectors are then presented, together with the techniques used to measure fluxes and spectra. Finally, the instruments and their limits are discussed to assist readers in choice of setup, planning and execution of observations, and data reduction. The volume also includes worked examples and problem sets to improve student understanding; tables and figures in chapters su mmarize the state of the art of instrumentation and techniques.
The question of a possible temporal variation of the fundamental constants was raised by Paul Dirac in his "large number hypothesis" in 1937. Today it appears in the context of the search for a unified theory of the fundamental interactions. It touches both fundamental and applied physics, as the postulate of the unalterability of the constants is the foundation for modern metrology. The book presents reviews written by leading experts in the field. Focussing on the question of variations of the fundamental "constants" in time or space, the chapters cover the theoretical framework in which variations are expected and the search for variations of quantities like the fine-structure constant, the electron/proton mass ratio, g-factors of proton and neutron etc. in astrophysical and geophysical observations and in precision experiments with atomic clocks and frequency standards.
Stephen Hawking, the Lucasian Professor of Mathematics at Cambridge University, has made important theoretical contributions to gravitational theory and has played a major role in the development of cosmology and black hole physics. Hawking's early work, partly in collaboration with Roger Penrose, showed the significance of spacetime singularities for the big bang and black holes. His later work has been concerned with a deeper understanding of these two issues. The work required extensive use of the two great intellectual achievements of the first half of the Twentieth Century: general relativity and quantum mechanics; and these are reflected in the reprinted articles. Hawking's key contributions on black hole radiation and the no-boundary condition on the origin of the universe are included. The present compilation of Stephen Hawking's most important work also includes an introduction by him, which guides the reader though the major highlights of the volume. This volume is thus an essential item in any library and will be an important reference source for those interested in theoretical physics and applied mathematics. It is an excellent thing to have so many of Professor Hawking's most important contributions to the theory of black holes and space-time singularities all collected together in one handy volume. I am very glad to have them". Roger Penrose (Oxford) "This was an excellent idea to put the best papers by Stephen Hawking together. Even his papers written many years ago remain extremely useful for those who study classical and quantum gravity. By watching the evolution of his ideas one can get a very clear picture of the development of quantum cosmology during thelast quarter of this century". Andrei Linde (Stanford) "This review could have been quite short: 'The book contains a selection of 21 of Stephen Hawking's most significant papers with an overview written by the author'. This would be sufficient to convince any researcher, student or librarian to acquire the book, so indisputable is the contribution of this man to the theoretical physics of the last half of our century ... Collected together, these brilliant works constitute a valuable contribution to the literature on modern classical and quantum gravity and cosmology. This book will certainly be a source of inspiration for new generations of physicists entering into this fascinating area of research". D Gal'tsov Classical & Quantum Gravity |
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