Current-driven flare and CME models

Abstract:

Magnetic energy released explosively (timescale: hundreds to thousands of seconds) in the impulsive phase of a solar flare, or in the acceleration of a CME, builds up in active regions over a relatively long time (days to weeks) prior to the flare/CME. The energetically important currents flow along coronal flux tubes and close deep inside the Sun. There is insufficient time for either the magnetic flux or the current passing through the solar surface to change significantly during a flare/CME. In this talk, I review the development of ideas on how energy release occurs subject to these constraints, starting with the early models of Giovanelli in the 1940s and Sweet in the 1950s, quadrupolar flare models of the 1980s and 1990s, and more recent skeleton models for 3D reconnection. I argue that important aspects of the physics involved in reconnecting, current-carrying flux tubes are not included in models, and are inadequately understood.