Pseudostreamer influence on flux rope evolution

TL;DR

This study uses numerical simulations to explore how pseudostreamers influence flux rope eruptions in the solar corona, revealing the importance of magnetic null points and flux in eruption dynamics.

Contribution

It provides the first detailed analysis of flux rope behavior near pseudostreamers using 2.5D MHD simulations, highlighting the role of magnetic nulls and flux in eruption outcomes.

Findings

Magnetic null points determine flux rope deflection and eruption potential.

Pseudostreamer lobes act as magnetic cages affecting flux rope confinement.

Total unsigned magnetic flux of the cage influences whether the flux rope erupts.

Abstract

A critical aspect of solar activity is the coupling between eruptions and the surrounding coronal magnetic field, which determines the trajectory and morphology of the eruptive event. Pseudostreamers (PSs) are coronal magnetic structures formed by arcs of twin loops capped by magnetic field lines from coronal holes of the same polarity that meet at a central spine. They contain a single magnetic null point in the spine, potentially influencing the evolution of nearby flux ropes (FRs). To understand the net effect of the PS on FR eruptions is first necessary to study diverse and isolated FR-PS scenarios, which are not influenced by other magnetic structures. We performed numerical simulations in which a FR structure is in the vicinity of a PS magnetic configuration. The combined magnetic field of the PS and the FR results in the formation of two magnetic null points. We evolve this scenario by numerically solving the magnetohydrodynamic equations in 2.5D. The simulations consider a fully ionised compressible ideal plasma in the presence of a gravitational field and a stratified atmosphere. We find that the dynamic behaviour of the FR can be categorised into three different classes based on the FR trajectories and whether it is eruptive or confined. Our analysis indicates that the magnetic null points are decisive in the direction and intensity of the FR deflection and their hierarchy depends on the topological arrangement of the scenario. Moreover, the PS lobe acts as a magnetic cage enclosing the FR. We report that the total unsigned magnetic flux of the cage is a key parameter defining whether the FR is ejected or not.