Dynamics of the Transition corona

TL;DR

This study investigates magnetic reconnection in pseudo-streamers, combining observations and simulations to reveal how open and closed magnetic fields exchange in the solar corona, highlighting a gradual reconnection process at null points.

Contribution

The paper introduces a novel observational technique and combines it with magnetic field modeling and 3D MHD simulations to analyze the dynamics of interchange reconnection in pseudo-streamers.

Findings

Reconnection occurs at null points within pseudo-streamers.

UV structures follow magnetic field evolution consistent with simulations.

Reconnection in pseudo-streamers is gradual, contrasting impulsive models.

Abstract

Magnetic reconnection between open and closed magnetic field in the corona is believed to play a crucial role in the corona/heliosphere coupling. At large scale, the exchange of open/closed connectivity is expected to occur in pseudo-streamer structures. However, there is neither clear observational evidence of how such coupling occurs in pseudo-streamers, nor evidence for how the magnetic reconnection evolves. Using a newly-developed technique, we enhance the off-limb magnetic fine structures observed with AIA and identify a pseudo-streamer-like feature located close to the northern coronal hole. After extrapolating the magnetic field with the PFSS model, we obtain a pseudo-streamer magnetic topology, null-point related topology bounded by open field. We compare the magnetic configuration with the UV observations and identify the magnetic structures expected to be involved in the event. Using an 3D MHD simulation of interchange reconnection, we showed that the evolution of the UV structures follows the magnetic field dynamics and the UV emitting structures have a pattern very similar to the plasma emission derived from the simulation. Our results highlight that the exchange between open and closed in the pseudo-streamer topology related to an observed event occurs at least partially at the null-point, similarly to the interchange reconnection in a single null-point topology. However, our results also indicate that the interchange reconnection in pseudo-streamers is a gradual physical process which opposes to the impulsive reconnection of the solar-jet model.