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EP: Fachverband Extraterrestrische Physik

EP 6: Sun and Heliosphere I

EP 6.3: Vortrag

Mittwoch, 18. März 2026, 14:45–15:00, KH 01.019

The Current Layer Missing in the Standard Model of Photospheric Flux Cancellation and CME Initiation — •Bernhard Kliem — Institute of Physics and Astronomy, University of Potsdam

Flux cancellation, driven by flows that converge at the polarity inversion line (PIL), is a common process in the evolution of photospheric magnetic flux. The standard model of photospheric flux cancellation predicts the formation and growth of a magnetic flux rope above the PIL, low in the corona (van Ballegooijen & Martens 1989). Consequently, the cancellation process is considered a pathway to CME initiation by magnetohydrodynamic (MHD) instability, which requires a flux rope to exist at the onset point. Recent MHD simulations of flux cancellation additionally reveal the formation of a vertical current layer or sheet between the PIL and the forming flux rope. This allows for CME initiation by tearing of the vertical current layer, which forms a plasmoid (seed flux rope) during the initiation of a subsequent eruption and is known as the reconnection model for CME initiation. MHD simulations of flux cancellation will be presented, which address the initiation of eruption by MHD instability vs. reconnection and its parametric dependence. Some runs reveal the formation of plasmoids in the slow-rise phase, merging with the main forming flux rope. This could be a model of confined precursor flares and can lead to a non-equilibrium state of the main rope prior to its eruption.