Solar-Terrestrial Physics Solar-Terrestrial Physics Solar-Terrestrial Physics 2500-0535 46200 10.12737/stp-81202202 Results of current research Results of current research Results of current research Small solar flares and local polarity inversion lines of the longitudinal magnetic field of the active region Small solar flares and local polarity inversion lines of the longitudinal magnetic field of the active region https://orcid.org/0000-0001-5725-8262 Боровик Александр Васильевич Borovik Aleksandr Vasil'evich aborovik@iszf.irk.ru

кандидат физико-математических наук;

candidate of physical and mathematical sciences;

 https://orcid.org/0000-0002-9563-1360 Жданов Антон Андреевич Zhdanov Anton Andreevich kick.out@mail.ru Институт солнечно-земной физики СО РАН Иркутск Россия Institute of Solar Terrestrial Physics SB RAS Irkutsk Russian Federation Институт солнечно-земной физики СО РАН Иркутск Россия Institute of Solar Terrestrial Physics SB RAS Irkutsk Russian Federation 25 03 2022 25 03 2022 8 1 19 23 11 10 2021 13 12 2021 https://zh-szf.ru/en/nauka/article/46200/view

Using photospheric data and data on the longitudinal magnetic field from the SDO satellite, as well as observations in the Hα line from GONG ground stations, we have studied the flare activity of the NOAA 12673 sunspot group, which in September 2017 produced the largest X9.3 class flare in the last decade. The active region was distinguished by rapid development, complex topology, and magnetic field dynamics. We have established that in the active region almost throughout the development period due to movements of diverse polar magnetic fluxes and their convergence, numerous local polarity inversion lines (LPIL) of the magnetic field were formed. Small solar flares have been found to be closely related to LPIL and to occur in those areas of LPIL where the gradient of the longitudinal magnetic field over time reaches maximum values.

Using photospheric data and data on the longitudinal magnetic field from the SDO satellite, as well as observations in the Hα line from GONG ground stations, we have studied the flare activity of the NOAA 12673 sunspot group, which in September 2017 produced the largest X9.3 class flare in the last decade. The active region was distinguished by rapid development, complex topology, and magnetic field dynamics. We have established that in the active region almost throughout the development period due to movements of diverse polar magnetic fluxes and their convergence, numerous local polarity inversion lines (LPIL) of the magnetic field were formed. Small solar flares have been found to be closely related to LPIL and to occur in those areas of LPIL where the gradient of the longitudinal magnetic field over time reaches maximum values.

 active regions small solar flares longitudinal magnetic field structure polarity inversion lines (PIL) active regions small solar flares longitudinal magnetic field structure polarity inversion lines (PIL) The work was performed with budgetary funding of Basic Research program II.16 and was supported by RFBR grant No. 19-52-45002 The work was performed with budgetary funding of Basic Research program II.16 and was supported by RFBR grant No. 19-52-45002

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