Sequential eruptions triggered by flux emergence - observations and modeling

TL;DR

This study combines solar observations and 3D magnetohydrodynamic simulations to analyze how flux emergence triggers sequential eruptions and filament splitting, emphasizing the importance of magnetic configuration in eruption prediction.

Contribution

It provides a detailed observational and modeling analysis of flux emergence-induced eruptions, highlighting the role of magnetic reconnection and the position of emerging flux.

Findings

Emerging flux can trigger filament splitting and eruptions within hours.

Magnetic reconnection episodes are key to eruption dynamics.

The position of flux emergence influences eruption outcomes.

Abstract

We describe and analyze observations by the Solar Dynamics Observatory of the emergence of a small, bipolar active region within an area of unipolar magnetic flux that was surrounded by a circular, quiescent filament. Within only eight hours of the start of the emergence, a partial splitting of the filament and two consecutive coronal mass ejections took place. We argue that all three dynamic events occurred as a result of particular magnetic-reconnection episodes between the emerging bipole and the pre-existing coronal magnetic field. In order to substantiate our interpretation, we consider three-dimensional magnetohydrodynamic simulations that model the emergence of magnetic flux in the vicinity of a large-scale coronal flux rope. The simulations qualitatively reproduce most of the reconnection episodes suggested by the observations; as well as the filament-splitting, the first eruption, and the formation of sheared/twisted fields that may have played a role in the second eruption. Our results suggest that the position of emerging flux with respect to the background magnetic configuration is a crucial factor for the resulting evolution, while previous results suggest that parameters such as the orientation or the amount of emerging flux are important as well. This poses a challenge for predicting the onset of eruptions that are triggered by flux emergence, and it calls for a detailed survey of the relevant parameter space by means of numerical simulations.