Recurrent explosive eruptions and the sigmoid-to-arcade transformation in the sun driven by dynamical magnetic flux emergence

TL;DR

This study uses 3D MHD simulations to explore recurrent eruptions in a solar active region, revealing a process where sigmoids transform into flare arcades following eruptions, with implications for understanding solar eruptions.

Contribution

It demonstrates how continuous magnetic flux emergence and reconnection lead to recurrent eruptions and sigmoid-to-arcade transformations in a simulated solar active region.

Findings

Recurrent mini CME-like eruptions driven by flux emergence.

Sigmoid structures reform after each eruption.

Eruptions are triggered by tether-cutting reconnection.

Abstract

We report on three-dimensional (3D) MHD simulations of recurrent mini CME-like eruptions in a small active region (AR), which is formed by the dynamical emergence of a twisted (not kink unstable) flux tube from the solar interior. The eruptions are developed as a result of repeated formation and expulsion of new flux ropes due to continous emergence and reconnection of sheared fieldlines along the polarity inversion line (PIL) of the AR. The acceleration of the eruptions is triggered by tether-cutting reconnection at the current sheet underneath the erupting field. We find that each explosive eruption is followed by reformation of a sigmoidal structure and a subsequent sigmoid-to-flare arcade transformation in the AR. These results might have implications for recurrent CMEs and eruptive sigmoids/flares observations and theoretical studies.