Impulsive coronal heating during the interaction of surface magnetic fields in the lower solar atmosphere

TL;DR

This study shows that impulsive heating of the solar corona is closely linked to magnetic reconnection events at the surface, especially where magnetic fields of opposite polarity interact, based on multi-instrument observations.

Contribution

It provides new observational evidence connecting surface magnetic interactions and impulsive coronal heating, highlighting magnetic reconnection as a key process.

Findings

Coronal loops with hot plasma often anchored in regions of magnetic polarity interaction.

Spectroscopic evidence of magnetic reconnection at the base of hot coronal loops.

Magnetic patch interactions at the surface are crucial for impulsive heating.

Abstract

Coronal plasma in the cores of solar active regions is impulsively heated to more than 5 MK. The nature and location of the magnetic energy source responsible for such impulsive heating is poorly understood. Using observations of seven active regions from the Solar Dynamics Observatory, we found that a majority of coronal loops hosting hot plasma have at least one footpoint rooted in regions of interacting mixed magnetic polarity at the solar surface. In cases when co-temporal observations from the Interface Region Imaging Spectrograph space mission are available, we found spectroscopic evidence for magnetic reconnection at the base of the hot coronal loops. Our analysis suggests that interactions of magnetic patches of opposite polarity at the solar surface and the associated energy release during reconnection are key to impulsive coronal heating.