1: Introduction and Summary.- 1. Preliminary Remarks.- 2. The Solar Interior.- 3. Atmosphere.- 4. The Sun in its Astrophysical Context.- 5. Solar-Terrestrial Relations.- References.- 2: Thermonuclear Reactions in the Solar Interior.- 1. Introduction.- 2. Reaction Rate Formalism.- 3. Carbon-Nitrogen Cycle.- 4. Proton-Proton Chain.- 5. Discussion and Conclusions.- References.- 3: Atomic and Radiative Processes in the Solar Interior.- 1. Introduction.- 2. Calculation of Atomic Structure.- 2.1. The Explicit Ion Model.- 2.2. The Mean Ion Model.- 3. Calculation of Opacity.- 3.1. Bound-Bound Processes.- 3.2. Bound-Free Processes.- 3.3. Free-Free Processes.- 3.4. Scattering Processes.- 3.5. Combining Processes to Obtain the Opacity.- 4. Results.- 5. Uncertainties in the Opacity.- Acknowledgements.- References.- 4: Hydrodynamic and Hydromagnetic Phenomena in the Deep Solar Interior.- 1. Introduction.- 2. Troublesome Observations.- 2.1. Light Element Depletion.- 2.2. Low 37CI Neutrino Counts.- 2.3. Possibility of Rapidly Rotating or Nonaxisymmetric Core.- 2.4. 160-Minute Oscillations.- 3. Theoretical Topics.- 3.1. Nucleo-Thermal Destabilizations of g-Modes.- 3.2. Depth of the Convective Zone.- 3.3. Two Topics not Discussed.- References.- 5: The Solar Dynamo: Observations and Theories of Solar Convection, Global Circulation, and Magentic Fields.- 1. Introduction.- 2. Convective Zone Characteristics.- 2.1. Basic Structure of Depth.- 2.2. Oblateness and Latitudinal Temperature Differences.- 2.3. Luminosity and Radius Changes.- 3. Observations and Theory of Solar Convection Zone Motions.- 3.1. Granulation.- 3.1.1. Observations.- 3.1.2. Granulation theory.- 3.2. Supergranulation and Mesogranulation.- 3.2.1. Observations.- 3.2.2. Theory.- 3.3. Related Theories of Convection.- 3.4. Global Circulation.- 3.4.1. Observations.- 3.4.2. Global circulation theory.- 4. Phenomenology of the Sun's Magnetic Field and Related Features.- 4.1. Flux Tubes and Network.- 4.2. Sunspots, Active Regions, and Global Patterns.- 4.3. The Solar Cycle: Manifestations in Sunspots, Magnetic Fields, and Other Properties.- 5. Theories of the Solar Magnetic Field.- 5.1. Flux Tubes and Network 13.- 5.2. Active Regions and Sunspots.- 5.3. Solar Dynamo Theory.- 6. Concluding Remarks 152 Acknowledgments.- References.- 6: Solar Internal Stresses: Rotation and Magnetic Fields.- 1. Introduction.- 2. Theory.- 2.1. Eddington-Sweet Circulation.- 2.2. Rotationally Driver Instabilities.- 2.3. An Internal Magnetic Field.- 3. Observations.- 4. Summary.- References.- 7: Solar Waves and Oscillations.- 1. Theory of Waves and Oscillations.- 1.1. Basic Equations.- 1.1.1. Full hydromagnetic equations.- 1.1.2. Linearized equations.- 1.2. Waves.- 1.2.1. Nonmagnetic waves.- 1.2.2. Magnetohydrodynamic waves.- 1.3. General Properties of Solar Oscillations.- 1.3.1. Equations and spheroidal mode solutions.- 1.3.2. Cowling approximation.- 1.3.3. Asymptotic behavior of p- and g-mode frequencies.- 1.3.4. Radial oscillations.- 1.3.5. Properties of nonadiabatic solutions.- 1.3.6. Toroidal oscillations.- 1.4. Excitation and Damping of Solar Pulsations.- 1.4.1. Excitation and damping mechanisms.- 1.4.2. Mode lifetimes.- 1.4.3. Stability of solar pulsation modes.- 1.5. Detailed Solutions for Frequencies and Frequency Splitting.- 1.5.1. Effects of structure on unperturbed frequencies.- 1.5.2. Effects of rotation.- 1.5.3. Effects of internal magnetic fields.- 1.6. Future Theoretical Needs.- 2. Observations.- 2.1. Observational Techniques.- 2.1.1. Diagnostics of spectrum lines.- 2.1.2. Techniques for observing oscillations and trapped waves.- 2.2. Oscillations Observed.- 2.2.1. Observations of 5 minute period p-mode oscillations.- 2.2.2. The 160 minute oscillation.- 2.2.3. Torsional oscillations.- 2.2.4. Localized brightness oscillations.- 2.3. Wave Observations.- 2.4. Waves and Oscillations in Sunspots.- 2.5. Future Observational Needs.- 3. Oscillations as Probes of the Solar Interior.- 3.1. Introduction.- 3.2. Direct Method.- 3.2.1. Technique.- 3.2.2. Direct method: results.- 3.3. Inversion Methods.- 3.3.1. Technique.- 3.3.2. Applications.- Acknowledgements.- References.

This volume, together with its two companion volumes, originated in a study commis­ sioned by the United States National Academy of Sciences on behalf of the National Aeronautics and Space Administration. A committee composed of Tom Holzer, Dimitri Mihalas, Roger Ulrich and myself was asked to prepare a comprehensive review of current knowledge concerning the physics of the Sun. We were fortunate in being able to persuade many distinguished scientists to gather their forces for the preparation of 21 separate chapters covering not only solar physics but also relevant areas of astrophysics and solar-terrestrial relations. It proved necessary to divide the chapters into three separate volumes that cover three different aspects of solar physics. Volumes II and III are concerned with 'The Solar Atmosphere' and with 'Astrophysics and Solar-Terrestrial Relations'. This volume is devoted to 'The Solar Interior', except that the volume begins with one chapter reviewing the contents of all three volumes. Our study of the solar interior includes a review of nuclear, atomic, radiative, hydrodynamic and hydromagnetic processes, together with reviews of three areas of active current investigation: the dynamo mechanism, internal rotation and magnetic fields, and oscillations. The last topic, in particular, has emerged in recent years as one of the most exciting areas of solar research.