The Solar Chromosphere and Corona: Quiet Sun

The widespread tendency in solar physics to divide the solar atmosphere into separate layers and to distinguish phenomena of solar activity from phenomena of the quiet Sun emphasizes the wide ranging diversity of physical conditions and events occurring in the solar atmosphere. This diversity spans the range from a neutral, essentially quiescent atmosphere to a highly ionized, violently convective atmosphere; from a domain in which magnetic field effects are unimportant to a domain in which the magnetic pressure exceeds the gas pressure, and from a domain in which the particle motions are Maxwellian to a domain in which an appreciable fraction of the particles is accelerated to relativistic energies. It is now widely recognized that the chromosphere and corona have a common origin in the mechanical energy flux generated in the hydrogen convection zone lying beneath the photosphere. Furthermore, magnetic field phenomena appear to be as vital to the structure of th~ quiet Sun as to the active Sun. For these reasons it appears desirable to present a unified treatment of the entire solar atmosphere, both active and quiet, in a single volume. On the other hand, such a treatise must be very long if it is to avoid being superficial, and it is very difficult for a single author to write authoritatively on such a wide range of topics.

I. Introduction.- 1. Chromospheres and Coronas.- 2. Goals for Solar Physics.- 3. Chromosphere and Coronal Boundaries.- 4. Methods of Observation.- 5. The K- and F-Coronas.- 6. Comments on Discrete Geometrical Features.- 7. Depths of Line Formation.- II. Structural Features.- 1. Observational Methods.- 2. The Photospheric Structure.- 3. Chromospheric Network.- 4. Chromospheric Fine Structure on the Disk.- 5. Spicule Structure.- 6. Transition Region Structure.- 7. Non-Spherical Modeling.- 8. Chromospheric Active Region Structure.- 9. Observations of Coronal Structures.- 10. Fine Structure of Inner Corona.- 11. Coronal Streamers.- 12. Coronal Rays and Plumes.- 13. Coronal Disk Structures and Coronal Holes.- 14. Prominences.- 15. Solar Cycle Effects.- III. Macroscopic Motions.- 1. Measuring Systematic Motions.- 2. Photospheric Motions.- 3. Chromospheric Motions.- 4. Small Scale Coronal Motions.- 5. Coronal Expansion: The Solar Wind.- 6. Prominence Motions.- 7. Impulsive Motions.- 8. Mass Balance and Energy Transport in Mass Flow.- IV. Magnetic Fields.- 1. Method of Observation.- 2. Energy Considerations.- 3. Polar Fields and UM Regions.- 4. Evolution of Large Scale Fields.- 5. Structure and Evolution of Small Scale Fields.- 6. Coronal Magnetic Fields.- V. Spectral Characteristics.- 1. Visual and Near Infrared Disk.- 2. Visual and Near Infrared Limb.- 3. Infrared, Radio and XUV Continuum Data.- 4. XUV Emission Lines.- VI. Analytical Methods for Spectroscopic Data.- 1. Scattering Continuum.- 2. Bound-Free Continua: Effectively Thin Case.- 3. Free-Free Continua.- 4. Total Line Intensities: Effectively Thin Case.- 5. Profiles of lines and Bound-Free Continua: Effectively Thick Case.- VII. Empirical Chromospheric and Coronal Models.- 1. Summary Models.- 2. Conditions at the Optical Limb.- 3. The Temperature Minimum Region.- 4. The Low Chromosphere.- 5. The Middle Chromosphere.- 6. The High Chromosphere.- 7. The Chromosphere-Corona Transition Region.- 8. The Corona.- VIII. Chromospheric Structure Inferred from Spectral Lines.- 1. Chromospheres and Coronas as Phenomena of Stellar Atmospheres.- 2. Influence of the Chromospheric Temperature Rise.- 3. Influence of the Chromospheric Increase in Doppler Width.- 4. Ca ii lines.- 5. Mg ii Lines.- 6. Neutral Metal Lines.- 7. Hydrogen Lines.- 8. C ii and O i Lines.- 9. Summary.- IX. Energy and Momentum Balance.- 1. Energy Balance.- 2. Radiation Loss Rates.- 3. Thermal Stability.- 4. Coronal Energy Loss by Thermal Conduction and Evaporation.- 5. Energy Balance Within the Transition Region.- 6. The Base of the Transition Region.- 7. The Effect of Motions.- 8. Energy Losses from the Chromosphere.- 9. The Quiet Sun Solar Wind.- 10. Spicule Mechanisms.- X. Wave Generation and Heating.- 1. Wave Generation.- 2. Interpretation of 5 Minute Oscillations.- 3. Generation of Waves by the Convection Zone.- 4. Heating.- 5. Acoustic Production of Stellar Chromospheres and Coronas.