History and basic characteristics of eruptive flares

Abstract

We review the evolution of our knowledge and understanding of the eruptive (dynamic, two-ribbon) flare phenomenon. Starting with the first observation of a white-light flare by Carrington and Hodgson in 1859, we cover in succession the highlights: Hale's invention of the spectroheliograph in 1892 and the spectrohelioscope in 1926 started flare observations in Hα. The institution of a world-wide flare patrol brought significant advances in knowledge of flares in the 1930s and 1940s and new ‘windows’ were opened to observe flares at short (SID) and long (radio) wavelengths. In the 1950s and 1960s metric radio bursts were related to trapped energetic electrons and shocks, and two-ribbon flares were associated with energetic protons in space. Radio and X-ray observations gave evidence for two basic types of flare processes: an impulsive phase followed by a long-duration or gradual phase. It was found that flares were often preceded by filament activations, and growing loop prominence systems were recognized as the limb counterpart of two-ribbon disk flares. The early 1970s brought Skylab observations of coronal mass ejections (CMEs) and arcades of coronal soft X-ray loops above two-ribbon flares. In the mid-1970s, the Kopp-Pneuman reconnection model, based on configurations proposed earlier by Carmichael, Sturrock, and Hirayama, provided a framework in which the newly discovered CMEs could be related to the basic characteristics of two-ribbon flares. The 1980s brought, key new results from SMM and Hinotori including images of hard X-ray flares and large-scale coronal structures associated with eruptive flares. In the conclusion, we summarize the basic characteristics of eruptive flares.KeywordsCoronal Mass EjectionSolar PhysSolar FlareRadio BurstSolar Energetic ParticleThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.