Final Report Summary - SEISMOSUN (Magnetohydrodynamic Wave Diagnostics of the Solar Atmosphere in the Era of Transformative High-Resolution Observations)
The main aim of the project was to design and apply the novel technique for the diagnostics of the plasma in the upper part of the solar atmosphere by wave and oscillatory motions detected in the Extreme Ultraviolet band with high-precision spaceborne imaging telescope Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory, and also in other bands, such as optical, X-rays and radio with the use of other observational facilities of the new generation. Analysis of observations was supplemented by state-of-the-art numerical modelling and theory. The analysis was performed with innovative data analysis techniques designed by the project team. The specific novel diagnostic techniques designed by the project team include the determination of the vertical structure of the plasma heating; the determination of the transverse fine, sub-resolution profile of the filamentation of the plasma; estimation of the confidence level of intrinsic modes detected by the Empirical Mode Decomposition method; innovative technique of Motion Magnification, which allows one to detect transverse motions with the amplitude well below the instrumental pixel size; diagnostics of the perpendicular profile of the plasma in coronal funnels by fast magnetoacoustic wave trains; and novel technique for probing microphysics processes by macroscopic observables. The project contributed to answering important questions of solar plasma physics: the identification of the excitation mechanism for decaying kink oscillations of coronal plasma loops; and demonstration of the nonlinear nature of the wave damping. In addition, we detected the new, decayless regime of kink oscillations of plasma loops, revealed its plasma diagnostic potential, and established the self-oscillatory nature of this phenomenon. These findings significantly advance our understanding of the basic physical processes operating in the solar corona, and, in particular, create a solid foundation for the development of new techniques for space weather forecasting. A very promising outcome of the project is the demonstration of the statistical significance of quasi-periodic pulsations detected in solar and stellar flares. Moreover, it was established that those pulsations have very similar properties, which suggests the similarity of the physical mechanisms responsible for the flares. In particular, this similarity is important for the assessment of the probability of the Sun producing a devastating superflare, similar to those observed on sun-like stars. Research visits and the project workshop funded by the grant allowed the project team to establish new and develop existing mutually beneficial collaborative links within and outside the EU, especially with the leading research institutions in China, Japan, Russia and S. Korea. In addition, the project results provide us with a basis for the effective exploitation of the upcoming observational facilities, such as the Square Kilometre Array, Solar Orbiter, and Proba-3. Two PhD students supported by the grant received comprehensive training in all aspects of the project research, and have successfully gained the PhD degrees. Two post-doctoral research assistants have gained permanent academic positions, and four others continue the development of their academic careers. Results obtained in the project were included in undergraduate lecture courses at the University of Warwick, lectures given at international summer schools for early career researchers, and in public lectures. The results have been published in about 70 refereed papers in leading international scientific journals, and were disseminated in fifteen invited talks (including plenary and keynote) at major international research conferences.