Theoretical Studies on the Evolution of Solar Filaments in Response to New Emerging Flux

Abstract

New emerging flux (NEF) has long been considered a mechanism for solar eruptions, but detailed process remains an open question. In this work, we explore how NEF drives a coronal magnetic configuration to erupt. This configuration is created by two magnetic sources of strengths $M$ and $S$ embedded in the photosphere, one electric-current-carrying flux rope (FR) floating in the corona, and an electric current induced on the photospheric surface by the FR. The source $M$ is fixed accounting for the initial background field, and $S$ changes playing the role of NEF. We introduce the channel function $C$ to forecast the overall evolutionary behavior of the configuration. Location, polarity, and strength of NEF governs the evolutionary behavior of FR before eruption. In the case of $|S/M|<1$ with reconnection occur between new and old fields, the configuration in equilibrium evolves to the critical state, invoking the catastrophe. In this case, if polarities of the new and old fields are opposite, reconnection occurs as NEF is close to FR; and if polarities are the same, reconnection happens as NEF appears far from FR. With different combinations of the relative polarity and the location, the evolutionary behavior of the system gets complex, and the catastrophe may not occur. If $|S/M|>1$ and the two fields have opposite polarity, the catastrophe always takes place; but if the polarities are the same, catastrophe occurs only as NEF is located far from FR; otherwise, the evolution ends up either with failed eruption or without catastrophe at all.

18 pages, 7 figures, accepted by ApJL