3D potential extrapolation of coronal magnetic field of active regions shows the overall configuration of open and closed magnetic field lines in the corona based on photospheric magnetic data. For two cases studied in this project (Bogomolov et al. 2018), the potential extrapolation of AR 10314 (associated with an X-class flare and small flux of solar energetic particles) revealed a high arcade, overlapping low lying sigmoid-like structures. In contrast, the unipolar sunspot of the AR 10588 (producing C-class flare and an order of magnitude larger SEP flux, respectively) had substantial amount of opened magnetic field lines. Thus, a significant difference in the large-scale magnetic field structure of ARs could be the explanation why lower soft X-ray class flare events could have a greater particle impact on Earth compared to the larger class flares. I n summary, the results of the comparative study performed during this project by Bogomolov et al. (2018) showed that the presence of open magnetic lines opposite to closed loop arcade should be an indicator of SEP productivity.
We carried out the study of the set of SEP productive flares and related ARs for the current 24th solar cycle (see examples of ARs in Figure 1). The events of the set were chosen among the solar flares observed in microwaves by 4-8 GHz spectropolarimeter. Unexpectedly we did not confirm the first result in spite of physical reasons predicting a good correlation.
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Figure 1. Left panel: Example of closed magnetic field configuration of the event 2012-01-23. | |
Most possibly the suggested algorithm based on the 3D reconstruction of magnetic field lines should be modified and information of type III presence should be added. The conclusions made on the base of the extrapolation procedure turned out to contain subjectivity while selecting which field lines to be visualized. One can see, there are two different examples of magnetic field visualization based on the same 3D extrapolation (Figure 2). Namely, a follow-up extrapolation was independently performed that resulted in a slightly different amount of open-to-closed field lines, which modifies the interpretation to a degree. Thus, we propose that solar radio emission signatures (e.g., radio bursts of type III) should be used as indicators of open field lines in the solar corona in addition to the information provided by the 3D potential magnetic field extrapolation.
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Figure 2. Examples of two different magnetic line vizualizations based on the same 3D magnetic filed extrapolation. |
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Publication
Bogomolov A, Myagkova I., Myshyakov I., Tsvetkov Ts, Kashapova L., Miteva R., Comparative analysis of the proton generation efficiency during 17 March 2003 and 11 April 2004 solar flares (2018), JASTP, Vol. 179, pp. 517÷526
