Solar Flare Modelling and Magnetic Reconnection

Active regions are host to strong magnetic fields with interesting connectivity features. Indeed magnetic fields play a vital role in providing stability and supporting structures such as cool, dense filaments or the containment of plasma, tracing vast coronal arcades. In contrast to such equilibrium solutions, the magnetic field also underlies extreme dynamical events - notably solar flares!

Solar flares correspond to a sudden release of pent up magnetic energy and are observed as intense emission signatures in the hard x-ray and UV regime. Modelling such energetic events is therefore not only important from an academic point of view but also from a practical perspective. Solar flares often act as a precursor to Coronal Mass Ejections (CME's) where plasma escapes the sun and is hurtled into interplanetary space. If this collides with the Earth, geomagnetic storms can have a major impact on our technology reliant world. Furthermore the enegetic EM emissions could also be harmful to humans.

One favourable approach to modelling solar flares examines a reconnection event whereby the topology of magnetic field lines changes - creating bent flux tubes. The reconnected field lines are accelerated by magnetic tension forces, snappng back into a straigt configuration akin to the relaxation of an elastic band. This accelerates plasma flows and generates the high temperatures and densities required to match the observed emission spectra.

Over the course of my project I will be using Professor Longcope's Post-Reconnection Evolution of a Flux Tube (PREFT) numerical model to investigate the applicability of the above ideas to solar flares. By initialising flux tubes with different parameters we can examine various evolutions. We can then combine the associated emission spectra using some time weighted convolution technique - thus simulating the net emission spectrum of a solar flare. Comparison with real life observations will hopefully corroborate this model.

Ⓒ Callum Fairbairn 2017