Equilibrium Plasma Structures in the Solar Atmosphere

A number of formations are observed in the atmosphere of the Sun demonstrating certain plasma structures that have been in equilibrium in the coronal magnetic field for a long time. Solar prominences were discovered long ago during total eclipse observations. Their types, properties, and magnetic structure are described. The location of prominences on the solar disk and their internal fine structure suggest that prominence plasma is supported and controlled by the magnetic field. All present day prominence models are based on one or other magnetic configuration that creates the magnetic skeleton of the prominence. Other conspicuous plasma structures observed in the corona are coronal cavities, coronal streamers, and polar plumes. Their properties are also briefly discussed.