Solar Magnetic Phenomena

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.

This book addresses and reviews many of the still little understood questions related to the processes underlying planetary magnetic fields and their interaction with the solar wind. With focus on research carried out within the German Priority Program ”PlanetMag”, it also provides an overview of the most recent research in the field. Magnetic fields play an important role in making a planet habitable by protecting the environment from the solar wind. Without the geomagnetic field, for example, life on Earth as we know it would not be possible. And results from recent space missions to Mars and Venus strongly indicate that planetary magnetic fields play a vital role in preventing atmospheric erosion by the solar wind. However, very little is known about the underlying interaction between the solar wind and a planet’s magnetic field. The book takes a synergistic interdisciplinary approach that combines newly developed tools for data acquisition and analysis, computer simulations of planetary interiors and dynamos, models of solar wind interaction, measurement of ancient terrestrial rocks and meteorites, and laboratory investigations.

The concept of summerschools and workshops at the Kanzelh· ohe · Solar Observatory, Karn · · ten, Austria, devotedtoup-to-datetopicsinsolarphysics has been proven to be extremely successful, and thus in August/September 2003 the third combined summerschool and workshop was held there. This book contains the proceedings of the Summerschool and Wo- shop "Solar Magnetic Phenomena" held from 25 August to 5 September 2003 at the Solar Observatory Kanzelh· ohe, · which belongs to the Institute for Geophysics, Astrophysics and Meteorology of the University of Graz, Austria. The book contains the contributions from six invited lecturers. They give an overview on the following topics: observations of the pho- sphere and chromosphere, solar?are observations and theory, coronal mass ejections and the relevance of magnetic helicity, high-energy radiation from the Sun, the physics of solar prominences and highlights from the SOHO mission. The lectures contain about 25 to 30 pages each and provide a valuableintroduction to the topics mentioned above. The comprehensive lists ofreferences at theendof each contribution enablethe interested reader to go into more detail. The second part of the book contains contributed papers. These - pers were presented anddiscussed in theworkshop sessions during the afternoons. The sessions stimulated intensive discussions between the p- ticipants and lecturers

This timely volume provides the first comprehensive review and synthesis of current understanding of magnetic fields in the Sun and similar stars. Magnetic activity results in a wealth of phenomena - including starspots, non-radiatively heated outer atmospheres, activity cycles, deceleration of rotation rates, and even, in close binaries, stellar cannibalism - all of which are covered clearly and authoritatively. This book brings together for the first time recent results in solar studies and stellar studies. The result is an illuminating new view of stellar magnetic activity. Key topics include radiative transfer, convective simulations, dynamo theory, outer-atmospheric heating, stellar winds and angular momentum loss. Researchers are provided with a state-of-the-art review of this exciting field, and the pedagogical style and introductory material make the book an ideal and welcome introduction for graduate students.

I have felt the need for a book on the theory of solar magnetic fields for some time now. Most books about the Sun are written by observers or by theorists from other branches of solar physics, whereas those on magnetohydrodynamics do not deal extensively with solar applications. I had thought of waiting a few decades before attempting to put pen to paper, but one summer Josip Kleczek encouraged an im mediate start 'while your ideas are still fresh'. The book grew out of a postgraduate lecture course at St Andrews, and the resulting period of gestation or 'being with monograph' has lasted several years. The Sun is an amazing object, which has continued to reveal completely unexpected features when observed in greater detail or at new wavelengths. What riches would be in store for us if we could view other stars with as much precision! Stellar physics itself is benefiting greatly from solar discoveries, but, in tum, our understanding of many solar phenomena (such as sunspots, sunspot cycles, the corona and the solar wind) will undoubtedly increase in the future due to their observation under different conditions in other stars. In the 'old days' the solar atmosphere was regarded as a static, plane-parallel structure, heated by the dissipation of sound waves and with its upper layer expanding in a spherically symmetric manner as the solar wind. Outside of sunspots the magnetic field was thOUght to be unimportant with a weak uniform value of a few gauss.

How are large-scale magnetic fields generated in the Sun in self-excited dynamo processes? And how are magnetic structures spontaneously formed in the Sun and how do they interact with the convective flows, storage and release of magnetic energy? These are just several of the fundamental questions answered in this timely review of our understanding of solar magnetic fields. This volume collects together review articles and research papers from an international conference, held in Freiburg, Germany, dedicated to the study of magnetic fields in the Sun. From large-scale patterns and global dynamo action to tiny flux tubes, from the overshoot layer below the convection zone up to the corona, and from instrumental problems and theoretical methods to the latest ground-based and satellite observations, this volume provides an essential review of our knowledge to date for graduate students and researchers.

These are the Proceedings of Colloquium No. 153 of the International Astro nomical Union, held at Makuhari near Tokyo on May 22 - 26, 1995, and hosted by the National Astronomical Observatory. This meeting was intended to be an interdisciplinary meeting between re searchers of solar and stellar activity, in order for them to exchange the newest information in each field. While each of these areas has seen remarkable advances in recent years, and while the researchers in each field have felt that information from the other's domain would be extremely useful in their own work, there have not been very many opportunities for intensive exchanges of information between these closely related fields. We therefore expected much from this meeting in pro viding stellar researchers with new results of research on the counterparts of their targets of research, spatially and temporarily resolved, as observed on the Sun. Likewise we hoped to provide solar researchers with new results on gigantic ver sions of their targets of research under the very different physical circumstances on other active stars. It was our greatest pleasure that we had wide attendance of experts and active researchers of both research fields from all over the world. This led to extremely interesting talks and very lively discussions, thereby stimulating the exchange of ideas across the fields.

This symposium was held at the College de France in Paris from August 31 to Sep tember 4, 1970. The Organizing Committee consisted of V. Bumba, R. Howard (Chairman), K. O. Kiepenheuer, R. Michard, E. N. Parker, A. B. Severny, V. E. Stepanov, and T. Takakura. The Local Organizing Committee consisted of Miss G. Drouin (Secretary), R. Michard (Chairman), J. -C. Pecker, and J. Rayrole. We are indebted to the College de France for their kind hospitality. I wish to express my gratitude to members of the Organizing Committee for advice and assistance and to R. Michard and the Local Organizing Committee, who were responsible for the smooth running of the sessions, the distribution and collection of the discussion sheets, and for a delightful Wednesday afternoon excursion to Meudon. It is a pleasure to thank J. W. Evans, V. E. Stepanov, K. O. Kiepenheuer, R. G. Giovanelli, T. G. Cowling, V. Bumba, W. C. Livingston, and J. M. Wilcox who kindly served as session chairmen. I also wish to thank Miss Judy Harstine and John M. Adkins of the Hale Observatories, for invaluable assistance in editing the proceedings. This Symposium has been supported financially by the International Astronomical Union.