Topological model of the anemone microflares in the solar chromosphere

Abstract

Context: The chromospheric anemone microflares, which were discovered by Hinode satellite about a decade ago, are specific transient phenomena starting from a few luminous ribbons on the chromospheric surface and followed by an eruption upward. While the eruptive stage was studied in sufficient detail, a quantitative theory of formation of the initial multi-ribbon structure remains undeveloped until now. Aims: We construct a sufficiently simple but general model of the magnetic field sources that is able to reproduce all the observed types of luminous ribbons by varying only a single parameter. Methods: As a working tool, we employed the Gorbachev-Kel'ner-Somov-Shvarts (GKSS) model of the magnetic field, which was originally suggested about three decades ago to explain fast ignition of the magnetic reconnection over considerable spatial scales by tiny displacements of the magnetic sources. Quite unexpectedly, this model turns out to be efficient for the description of generic multi-ribbon structures in the anemone flares as well. Results: As follows from our numerical simulation, displacement of a single magnetic source (sunspot) with respect to three other sources results in a complex transformation from three to four ribbons and then again to three ribbons, but with an absolutely different arrangement. Such structures closely resemble the observed patterns of emission in the anemone microflares.