Coronal Expansion and Solar Wind

Little more than ten years have passed since spaceprobe-borne instruments con­ clusively demonstrated the existence of the solar wind. These observations con­ firmed the basic validity of a theoretical model, first proposed by E. N. Parker, predicting a continuous, rapid expansion of the solar corona. The subsequent decade has seen a tremendous growth in both the breadth and sophistication of solar wind observations; the properties of the interplanetary plasma near the orbit of the earth are now known in great detail. The theory of the coronal ex­ pansion has also been highly refilled both in the sense of including additional physical processes, and of treating more realistic (time-dependent and non spheri­ cally-symmetric) coronal boundary conditions. The present volume is an attempt to synthesize the solar wind observations and coronal expansion models from this decade of rapid development. The ultimate goal is, of course, the interpretation of observed solar wind phenomena as the effects of basic physical processes occurring in the coronal and interplanetary plasma and as the natural manifestations of solar properties and structures. This approach implies an emphasis upon the "large-scale" features revealed by the observations. It requires extensive use of the concepts and methods of fluid mechanics.

Inhalt

I History and Background.- I.1 Introduction.- I.2 Indirect Evidence for the Existence of the Solar Wind.- I.3 The Extension of the Solar Corona into Interplanetary Space.- I.4 The Expansion of the Solar Corona into Interplanetary Space.- I.5 The Extension of the Solar Magnetic Field into Interplanetary Space.- I.6 An Alternative Model of the Coronal Expansion.- I.7 Confirmation of the Existence of the Solar Wind by In Situ Spacecraft Observations.- II The Identification and Classification of Some Important Solar Wind Phenomena.- II.1 Introduction.- II.2 The Classification of Solar Wind Phenomena.- II.3 An Identification, Description, and Classification of Some Solar Wind Phenomena.- Persistent, High-Speed Solar Wind Streams.- Flare-Produced Interplanetary Shock Waves.- Interplanetary Filaments.- Alfvén Waves.- Hydromagnetic Discontinuities.- II.4 Summary and Plan of Action.- III The Dynamics of a Structureless Coronal Expansion.- III.1 Introduction.- III.2 In Search of the Structureless Solar Wind.- III.3 The Physical Properties of Low-Speed Solar Wind.- III.4 A "One-Fluid" Model of the Steady, Spherically-Symmetric Coronal Expansion.- III.5 A "Two-Fluid" Model of the Steady, Spherically-Symmetric Coronal Expansion.- III.6 A Comparison of Solar Wind Observations with Predictions of the Basic One-Fluid and Two Fluid-Models.- III.7 The Energetics of the Coronal Expansion.- III.8 The Effects of Hydromagnetic Waves on the Coronal Expansion.- III.9 The Effects of Magnetic Forces on the Coronal Expansion.- III.10 The Effects of the Magnetic Modification of Heat Conduction on the Coronal Expansion.- III.11 The Effects of Viscosity on the Coronal Expansion.- III.12 The Effects of Noncollisional Energy Exchange Mechanisms on the Coronal Expansion.- III.13 The Effects of a Reduced Thermal Conductivity on the Coronal Expansion.- III.14 Another Look at the Energetics of the Coronal Expansion.- III.15 Angular Momentum in the Coronal Expansion.- III.16 Evaporative Models of the Coronal Expansion.- IV Chemical Composition of the Expanding Coronal and Interplanetary Plasma.- IV.1 Introduction.- IV.2 The Determination of the Average Solar Wind Helium Abundance.- IV.3 A Comparison of the Solar and Interplanetary Helium Abundances.- IV.4 Theoretical Models of the Expansion of a Corona Containing Helium.- IV.5 The Relationship between the Photospheric and Coronal Helium Abundances.- IV.6 General Conclusions Regarding the Chemical Composition of the Expanding Solar Atmosphere.- IV.7 Observations of Solar Wind Ions Other than 1H+ and 4He++.- IV.8 The Ionization State of Expanding Coronal Plasma.- (1) Collisional Ionization by Electron Impact.- (2) Radiative Recombination.- IV.9 Possible Interplanetary Modification of the Solar Wind Ionization State.- V High-Speed Plasma Streams and Magnetic Sectors.- V.1 Introduction.- V.2 Observed Features of High-Speed Plasma Streams.- V.3 Observed Features of Magnetic Sectors.- V.4 The Relationship between High-Speed Plasma Streams and Magnetic Sectors.- V.5 Theoretical Models of Interplanetary Plasma Streams.- V.6 Theoretical Models of the Nonuniform, Hydromagnetic Coronal Expansion.- V.7 The Effects of High-Speed Plasma Streams on Average Solar Wind Characteristics.- V.8 Energy Transport in High-Speed Solar Wind Streams.- V.9 The Solar Sources of High-Speed Plasma Streams.- VI Flare-Produced Interplanetary Shock Waves.- VI.1 Introduction.- VI.2 The Motions of Interplanetary Shock Waves Inferred from Plasma Observations.- VI.3 Shock Configurations Inferred from Magnetic and Plasma Observations.- VI.4 Characteristics of the Post-Shock Plasma and Magnetic Field.- VI.5 The Chemical Composition of the Post-Shock Plasma.- VI.6 The Relationship between Solar Flares and Interplanetary Shock Waves.- VI.7 A Synthesis of Interplanetary Shock Observations.- VI.8 Theoretical Models of Shock Propagation in the Solar Wind.- VI.9 A Classification of Interplanetary Shock Waves Suggested by the Theoretical Models.- VI.10 The Mass and Energy in Interplanetary Shock Waves.- VI.11 The Role of Interplanetary Shock Waves in the Overall Mass and Energy Transport from the Corona.- VI.12 Implications Regarding the Physics of Solar Flares.- VII Concluding Remarks.- VII.1 Neglected Topics.- (1) Techniques of Solar Wind Observations.- (2) Small-Scale Interplanetary Phenomena.- (3) Extensions of the Coronal Expansion Concept.- (4) Solar Wind Interactions with Other Particles, Fields, and Planetary Bodies.- (5) Formal Aspects of the Solar Wind Equations.- (6) Heliographic Latitude Dependencies of Solar Wind Properties.- VII.2 Solar Activity and the Solar Wind.- References.