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arXiv · 1807.00020

Sequential eruptions triggered by flux emergence - observations and modeling

Sally Dacie·Tibor Torok·Pascal Demoulin·Mark Linton·Cooper Downs·Lidia van Driel-Gesztelyi·David Long·James Leake
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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.

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Sally Dacie, Tibor Torok, Pascal Demoulin, Mark Linton, Cooper Downs, Lidia van Driel-Gesztelyi, David Long, James Leake. 2018-06-29. Sequential eruptions triggered by flux emergence - observations and modeling. https://doi.org/10.3847/1538-4357%2Faacce3

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