Proceedings of the 157th Symposium of the International Astronomical Union held in Potsdam, Germany, September 7--11, 1992

Astrophysical dynamos are at the heart of cosmic magnetic fields of a wide range of scales, from planets and stars to entire galaxies. This book presents a thorough, step-by-step introduction to solar and stellar dynamos. Looking first at the ultimate origin of cosmic seed magnetic fields, the antagonists of field amplification are next considered: resistive decay, flux expulsion, and flows ruled out by anti-dynamo theorems. Two kinematic flows that can act as dynamos are then studied: the Roberts cell and the CP-flow. Mean-field electrodynamics and derivation of the mean-field dynamo equations lead to the alpha Omega-dynamo, the flux transport dynamo, and dynamos based on the Babcock-Leighton mechanism. Alternatives to the mean-field theory are also presented, as are global MHD dynamo simulations. Fluctuations and grand minima in the solar cycle are discussed in terms of dynamo modulations through stochastic forcing and nonlinear effects. The book concludes with an overview of the major challenges in understanding stellar magnetic fields and their evolution in terms of various dynamo models, global MHD simulations, and fossil fields. Each chapter is accompanied by an annotated bibliography, guiding the readers to the relevant technical literature, which may lead them to carry out their own research in the field of dynamo theory.

Comprised of lectures for an intensive course held at the Newton Institute in Cambridge, as part of a NATO Advanced Study Institute, the topics covered within this volume include planetary and solar dynamos, fast dynamos, and the use of symmetry principles to derive evolution equations.

Nonlinear dynamo theory is central to understanding the magnetic structures of planets, stars and galaxies. In chapters contributed by some of the leading scientists in the field, this text explores some of the recent advances in the field. Both kinetic and dynamic approaches to the subject are considered, including fast dynamos, topological methods in dynamo theory, physics of the solar cycle and the fundamentals of mean field dynamo. Advances in Nonlinear Dynamos is ideal for graduate students and researchers in theoretical astrophysics and applied mathematics, particularly those interested in cosmic magnetism and related topics, such as turbulence, convection, and more general nonlinear physics.

This self-contained introduction to astrophysical magnetic fields provides a comprehensive review of the current state of the field and a critical discussion of the latest research. Its emphasis on results that are likely to form the basis for future progress benefits a broad audience of advanced students and active researchers.

The book presents the fundamental physics underlying our increased understanding of the early universe, the cosmic microwave background, large scale structure formation, the dark matter problem, and the interplay between them, focusing on the cosmic microwave background. There is an emphasis on the mutual impact of fundamental physics and cosmology, both at theoretical and experimental / observational levels, within a deep and well defined programme that additionally provides a careful interdisciplinarity. Special sections cover fractals and scaling laws in astrophysics and cosmology, and high energy and neutrino astrophysics. The nature of the domain demands different approaches and points of view (either complementary or contradictory). Readers are provided with the basics of the different competitive lines of research, affording them an excellent opportunity to learn about the real state of the disciplines and increasing their critical awareness. Readership: Experimental and theoretical physicists, astrophysicists and astronomers from a variety of backgrounds. An excellent reference for the young postdoctoral scientist. Also useful for advanced undergraduate students and senior scientists.

A fundamental, profound review of the key issues relating to the early universe and the physical processes that occurred in it. The interplay between cosmic microwave background radiation, large scale structure, and the dark matter problem are stressed, with a central focus on the crucial issue of the phase transitions in the early universe and their observable consequences: baryon symmetry, baryogenesis and cosmological fluctuations. There is an interplay between cosmology, statistical physics and particle physics in studying these problems, both at the theoretical and the experimental / observational levels. Special contributions are devoted to primordial and astrophysical black holes and to high energy cosmic rays and neutrino astrophysics. There is also a special section devoted to the International Space Station and its scientific utilization.

Modern observations, including recent ones with the Hubble Space Telescope, have revealed that the Universe is replete with plasma outflows from all kinds of objects, ranging from stars in all their variety to galaxies. In this masterly survey of plasma astrophysics, written by leading practitioners, the first 15 articles in Part I deal with the use of the MHD approach in several key problems of solar plasma, such as magnetoconvection and magnetic field generation, sunspots and coronal loops, magnetic nonequilibrium and coronal heating, coronal mass ejections, the acceleration of the solar wind, and stellar winds across the Main Sequence. The following 16 articles of Part II deal with the use of the same MHD approach in several central and puzzling aspects of more distant astrophysical plasmas, such as the dynamics of the interstellar medium, collimated outflows from young stellar objects and accretion disks, molecular outflows and jets associated with enigmatic binaries and symbiotic stars, relativistic flows associated with superluminal microquasars in our own galaxy, astrophysical jets from nearby galaxies, or remote active galactic nuclei and quasars, probably fuelled by supermassive black holes. The emphasis throughout is on the striking underlying similarities in the physics of all these problems. Audience: Indispensable for solar physicists and astrophysics alike. An ideal textbook for graduate students in physics and astrophysics.

Mean-Field Magnetohydrodynamics and Dynamo Theory provides a systematic introduction to mean-field magnetohydrodynamics and the dynamo theory, along with the results achieved. Topics covered include turbulence and large-scale structures; general properties of the turbulent electromotive force; homogeneity, isotropy, and mirror symmetry of turbulent fields; and turbulent electromotive force in the case of non-vanishing mean flow. The turbulent electromotive force in the case of rotational mean motion is also considered. This book is comprised of 17 chapters and opens with an overview of the general concept of mean-field magnetohydrodynamics, followed by a discussion on the back-reaction of the magnetic field on motion; the structure of the turbulent electromotive force; homogeneous and two-scale turbulence; turbulent electromotive force in the case of rotational mean motion; and the dynamo problem of magnetohydrodynamics. The dynamo theory, which is based on mean-field magnetohydrodynamics, is explained and its applications to cosmical objects are described. The remaining chapters explore toroidal and poloidal vector fields; a simple model of an a-effect dynamo; and spherical models of turbulent dynamos as suggested by cosmical bodies. This monograph will be of interest to physicists.

This volume presents the current knowledge of magnetic fields in diffuse astrophysical media. Starting with an overview of 21st century instrumentation to observe astrophysical magnetic fields, the chapters cover observational techniques, origin of magnetic fields, magnetic turbulence, basic processes in magnetized fluids, the role of magnetic fields for cosmic rays, in the interstellar medium and for star formation. Written by a group of leading experts the book represents an excellent overview of the field. Nonspecialists will find sufficient background to enter the field and be able to appreciate the state of the art.