Theory and observations of coronal shock waves

Abstract

Coronal shock waves are generated by flares and/or coronal mass ejections. They manifest themselves in solar type II radio bursts. The observational features of these radio bursts and their relationship to coronal mass ejections and interplanetary shocks are briefly reviewed. Finally, the various theoretical models of solar type II radio bursts are presented and compared with the observations. All these models base on the production of highly energetic electrons by coronal shock waves since nonthermal radio radiation is generally assumed as being generated by suprathermal electrons. These high energy electrons excite Langmuir waves or upper hybrid waves, which convert into radio waves.