The work of the project started with the decision of a suitable AR sample to be examined. This was chosen to be as diverse as possible regarding the level of activity and morphology of the individual ARs, and it consisted initially from nine ARs. After downloading the observational magnetometric data from the Helioseismic and Magnetic Imager (HMI) instrument of the Solar Dynamics Observatory (SDO), the next, and most demanding computationally, task was the reconstruction of the 3D coronal magnetic field for all ARs and all snapshots considered. This was done with a widely-used non-linear force-free extrapolation method and by using a high-performance computing facility in Greece. Starting from the 3D magnetic field, three more vector fields were computed: the appropriate potential magnetic field, and the respective vector potentials that generate the original and the potential magnetic fields. The final computational step in order to obtain RFLH was the field line integrations along the two magnetic fields. Since RFLH is generally a gauge-dependent quantity, its computation process was repeated with a different gauge setup.
Apart from RFLH, many other physical parameters of the ARs were estimated, such as various energies and magnetic helicities. The quality of the reconstructed coronal magnetic fields was also assessed with many metrics and only those with high levels of solenoidality were considered in the subsequent study.
The analysis of RFLH was restricted to the times around 28 big flares (above M-class) from seven ARs, and to the regions known as magnetic polarity inversion lines (PILs) where the magnetic field changes sign. The use of RFLH allowed us to estimate the relative magnetic helicity in these PILs, in addition to the other physical parameters. The comparison of the relative helicity of the PILs with their magnetic flux, a quantity known as the R-parameter and whose high values are related with strong solar flares, showed that the helicity-based R values are as good as the magnetic-field-based ones, and sometimes, outperform the traditional ones. Apart from these quantities, many other PIL-deduced parameters were examined as well, but they did not show similar potential in indicating solar eruptivity.
The results of the project were (and will be) published in two international peer-reviewed scientific journals. They were also disseminated through oral and poster presentations, physically or virtually, in eight international scientific conferences, both in Greece and abroad.
The researcher of the project also participated in outreach activities, at schools or with the general public, such as the online ‘Science is Wonderful! 2021’ event, or the ‘2022 European Researchers’ Night’ in Athens, Greece. He also gained experience in teaching activities at the host University and in familiarization with solar observations. More details for the project can be found at its webpage, at the address ‘myweb.uoi.gr/k.moraitis/elisity.html’, where links to individual results are given.
