Magnetic Fields In The Solar Atmosphere

This paper describes the magnetic field configurations observed in the solar atmosphere including the corona and the solar wind. The techniques for observing solar magnetic fields are briefly reviewed. The significance of Alfven waves in transporting energy is stressed. (Author).

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.

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.

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.

In September 1984 a Summer School on Solar System Plasmas was held at Imperial College with the support of the Science and Engineering Research Council. An excellent group of lecturers was assembled to give a series of basic talks on the various aspects of the subject, aimed at Ph. D. students or researchers from related areas wanting to learn about the plasma physics of the solar system. The students were so appreciative of the lectures that it was decided to write them up as the present book. Traditionally, different areas of solar system science, such as solar and magnetospheric physics, have been studied by separate communities with little contact. However, it has become clear that many common themes cut right across these distinct topics, such as magnetohydrodynamic instabilities and waves, magnetic reconnect ion , convection, dynamo activity and particle acceleration. The plasma parameters may well be quite different in the Sun's atmosphere, a cometary tailor Jupiter's magnetosphere, but many of the basic processes are similar and it is by studying them in different environments that we come to understand them more deeply. Furthermore, direct in situ measurements of plasma properties at one point in the solar wind or the magnetosphere complement the more global view by remote sensing of a similar phenomenon at the Sun.

This volume provides an in-depth review of all aspects of solar magnetic fields. Written by world-leading experts, these thirteen papers cover all regions of the subject from the solar interior, photosphere, chromosphere, active regions, and corona out to the solar wind. The history of solar magnetic fields as well as the necessary instrumentation are also covered. The volume serves as both a reference for researchers and a starting point for graduate students. Originally published in Space Science Reviews, Volume 210, Issue 1-4, September 2017

This volume is devoted to the dynamics and diagnostics of solar magnetic fields and plasmas in the Sun’s atmosphere. Five broad areas of current research in Solar Physics are presented: (1) New techniques for incorporating radiation transfer effects into three-dimensional magnetohydrodynamic models of the solar interior and atmosphere, (2) The connection between observed radiation processes occurring during flares and the underlying flare energy release and transport mechanisms, (3) The global balance of forces and momenta that occur during flares, (4) The data-analysis and theoretical tools needed to understand and assimilate vector magnetogram observations and (5) Connecting flare and CME phenomena to the topological properties of the magnetic field in the Solar Atmosphere. The role of the Sun’s magnetic field is a major emphasis of this book, which was inspired by a workshop honoring Richard C. (Dick) Canfield. Dick has been making profound contributions to these areas of research over a long and productive scientific career. Many of the articles in this topical issue were first presented as talks during this workshop and represent substantial original work. The workshop was held 9 – 11 August 2010, at the Center Green campus of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. This volume is aimed at researchers and graduate students active in solar physics, solar-terrestrial physics and magneto-hydrodynamics. Previously published in Solar Physics journal, Vol. 277/1, 2012.

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.