DescriptionParker's nanoflare model (1987) is widely used to describe the heating of the corona. However, the model is viable only if the number of events is large and covers the whole solar sphere. Klimchuk (2015) argued that more than 100,000 current sheets should exist in an active region to produce a sufficient heating of the corona up to 1 MK. In order to validate Klimchuk's model, we compare the magnetic field distribution in several action regions, from quiet to flare-productive regions. From different magnetic field models (i.e., potential, nonlinear force-free fields), we derive the existence of tangential discontinuities, signatures of current sheets. We obtain that, at a given time, there exists a large number of tangential discontinuities that have potentially a free energy of nano- to micro-flare energies. The current sheets are located at the bottom of the corona, but just a small number of current sheets is located high in the corona (>20 Mm) where the topology of the magnetic field is less tangled/twisted. The density of current sheets is constant in time. This analysis supports Klimchuk's argument regarding Parker's model, but also predicts energy releases at the picoflare scale.
|12 Apr 2019
|RAS Specialist Meeting: Flares on the Sun and stars