SERAF · Solar Eruptions and Flares: Bridging the scale gap

Solar Eruptions and Flares: Bridging the scale gap

Solar flares and eruptions are the most energetic phenomena in the solar system. As they are the major drivers of the space weather they have also significant impact on our hi-tech based modern civilization. Understanding their physics is therefore a key to their future predictions. The process of magnetic reconnection has been suggested for energy release in solar flares already many years ago. However, many questions remained open in application of the magnetic-reconnection theory to the physics of flares. Most notably it is an issue of huge scale separation between the flare size and the scale at which the energy dissipation is expected by theory. The project therefore aims on searching for mechanisms of fragmentation and filamentation of the electric currents in flares. In other words, what are the processes that transfer the magnetic energy from large to small scales. In order to answer this question advanced, high-resolution numerical simulations were developed and used. In the first period of the project we managed to develop, test, and use 2.5D MHD code based on least-square formulation of finite element method (LSFEM) with self-adaptive mesh. We confirmed the original expectation expressed in the project proposal that the cascade of magnetic flux-ropes / plasmoids plays a key role for the energy transfer to small scales. In particular, it was shown that the formation of smaller scale plasmoids in the current layer formed between two larger magnetic flux ropes (a.k.a. fragmenting coalescence) continues down to the kinetic scales. Moreover, role of the flows and waves/shocks created in the reconnection cascade for the further fragmentation of electric currents was newly revealed. We have also studied some 3D aspects of solar eruptions with our older code upgraded to 3D in frame of the project execution. We found scalings and spectra of the cascade in magnetic reconnection and showed they are in-line with theoretical expectations. Last but not least, we brought some evidence in favor of applicability of our model to real solar flares and eruptions by relating our model results to observations. In connection with that we are also preparing solar observations with the current top facility - observatory ALMA. The project execution has also significant impact on the career development of the researcher. During the first period he improved his classification and based on the scientific results managed to obtain the permanent position in the host institution. Consecutively he was also delegated to take positions in the executive of the institute (2012 Institute council Member, since 2013 Deputy Head of the Solar physics department, since 2014 head of the Czech node of the European ALMA Regional Center) - these can be considered as other milestones in his career development. In the same moment it brought benefit to the host institution and broader community via knowledge transfer: The researcher organized a couple of workshops, conferences and schools where he also acted as a lecturer. He is supervising one undergraduate and one PhD student in the field of his expertise. Researchers work on the project was recognized on the national (Award of Academy of Sciences) as well as international levels (invited talks on international conferences, elected member of the SCOSTEP and CESRA board).

Data: CORDIS, © European Union