Post-reconnection Processes: Shocks, Jets, and Microflares

Abstract

In the previous chapter, we began to study the reconnection of magnetic flux tubes under the photospheric conditions where magnetic energy is less than the gas-kinetic energy of surrounding plasma (β ≥ 1). We saw that unlike a low β reconnection that liberates large amount of magnetic energy leading to an in situ heating, high β reconnection does not give an immediate gain in energy, but it sets the system in a highly dynamic state triggering strongly nonlinear processes. These processes, determined by the evolution of post-reconnection products , occur higher in the atmosphere at a considerable distance from the reconnection area. In this chapter, we shall study how the post-reconnection products evolve and what determines the form and energetics of their impact on the overlying atmosphere. We will see that there are three major forms of the post-reconnection outcome: (1) generation of supersonic plasma jets, (2) formation of microflares, and (3) various combinations of jets and microflares. These were found to be in a perfect agreement with observations. Moreover, multiwavelength observations show details and interrelation of a ubiquitous sequence of events that start from cancellation of photospheric magnetic fields, pass through shock formation, and result in appearance of supersonic jets, microflares, and their combinations in the overlying atmosphere.