Chromospheric Fine Structure

The devotion of an IA U symposium entirely to the topic of chromo spheric fine structure at a time when models of the spherically symmetric chromosphere are still evolving constitutes a valid recognition of the growing feeling among solar astron­ omers that the chromosphere cannot be understood independently of its discrete structural features. Network structure, which seemingly borders the photospheric supergranule cells, persists intact throughout the chromosphere and most of the chromosphere-corona transition region. The network is the locus of the bright coarse mottles, and the spicule bushes and is the terminus for one end of the quiet chromo­ spheric fibrils as well. Additionally, it is the locus of most of the magnetic flux of the quiet chromosphere. It is not surprising, therefore, that current studies of the chromosphere tend to center around efforts to better describe the network phenom­ ena and to ascertain the physical properties of the network features. Clearly, the supergranule cells and associated network structures constitute a fundamental and singularly important feature of solar structure in the boundary layers. Just as it is now clear that much of the chromo spheric fine structure is associated with the network bordering supergranule cells, it seems equally clear that structural features are almost universally associated with both fluid flow and magnetic geometry. Indeed, many observers claim that the brightness features faithfully map the mag­ netic lines offorce while still others claim that associated with each class of brightness feature there is a more or less unique fluid flow.

I The Quiet Chromosphere: Limb Phenomena. - Spicules and Their Surroundings. - Radiation Pressure in Stellar Atmospheres with Application to Solar Spicules. - Chromospheric Fine Structures near the Solar Limb in H? . - Recent Developments in Improving Daytime Angular Resolution from the Ground. - Spatial and Spectral Structure of Chromospheric Lines. - II The Quiet Chromosphere: Disk Phenomena. - Why the Chromosphere has Its Discrete Fine Structure. - Properties of the Solar Filigree Structure. - Spicules are Bright and Dark. - High Resolution Spectroscopy of the Disk Chromosphere. III: Evidence for the Propagation and Dissipation of Mechanical Energy in the Chromosphere. - Comparison of H? and Caii H and K Spectroheliograms as a Diagnostic Probe. - Fine Structure of the Sun at Centimeter Wavelengths. - III The Upper Chromosphere. - Fine Structure of the Upper Chromosphere. - Further Observations of the Structure of the Chromosphere-Corona Transition Region from Limb and Disk Intensities. - Non-Static Structure of the Chromosphere-Corona Transition Region. - On the Design of Chromospheric Models. - IV Motion and Excitation in the Chromosphere. - Motions of Chromospheric Fine Structures. - Waves and Oscillations in the Chromosphere in Active and Quiet Regions. - Chromospheric Oscillations in Plages. - Trapped Oscillations in the Chromosphere in the Presence of a Magnetic Field. - V The Chromosphere in Active Regions. - The Magnetic Structure of Plages. - On Facular Models. - A Facula Model and Its Application to Facula Fine Structures. - The Relation between Chromospheric and Photospheric Structures in Sunspot Groups. - The Structure of the Prominence-Corona Interface. - Helical Field Lines in an Erupting Filament. - VI Evolution of Chromospheric Fine Structures. - Streaming Magnetic Features nearSunspots. - On the Relation between Moving Magnetic Features and the Decay Rates of Sunspots. - A Theoretical Model for the Convection of Magnetic Flux in and near Sunspots. - Evolution of Chromospheric Fine Structures on the Disk. - Evolution of Structures in the Bright H? Network. - H? Fine Structure and the Dynamics of the Solar Atmosphere. - VII Energy Balance, Heat Transfer and Heating Mechanisms in Chromospheric Fine Structures. - The Chromospheric Energy Balance. - Ray Trapping in Stellar Envelopes, Pulsational Instabilities and Heating of External Layers. - A Magnetic Model of the Chromosphere-Corona Transition Region. - Excess Heating of Corona and Chromo-sphere above Magnetic Regions by Non-Linear Alfvén Waves. - The Stability of a Magnetic Flux Rope and Its Relation to Sunspots, Faculae and Flares. - General Discussion. - Index of Subjects.