Key Aspects of Coronal Heating

TL;DR

Understanding coronal heating requires addressing impulsive energy release, magnetic structures, reconnection, nanoflares, and collective behaviors through coordinated observational and simulation efforts.

Contribution

This paper identifies ten key aspects of coronal heating that must be understood, emphasizing the need for integrated observational and simulation approaches.

Findings

Coronal heating is impulsive and involves elemental magnetic strands.

Current sheets and reconnection are central to energy release.

Nanoflares occur with varying frequencies and are not the main source of plasma.

Abstract

We highlight ten key aspects of coronal heating that must be understood before we can consider the problem to be solved. (1) All coronal heating is impulsive. (2) The details of coronal heating matter. (3) The corona is filled with elemental magnetic stands. (4) The corona is densely populated with current sheets. (5) The strands must reconnect to prevent an infinite buildup of stress. (6) Nanoflares repeat with different frequencies. (7) What is the characteristic magnitude of energy release? (8) What causes the collective behavior responsible for loops? (9) What are the onset conditions for energy release? (10) Chromospheric nanoflares are not a primary source of coronal plasma. Significant progress in solving the coronal heating problem will require a coordination of approaches: observational studies, field-aligned hydrodynamic simulations, large-scale and localized 3D MHD simulations, and possibly also kinetic simulations. There is a unique value to each of these approaches, and the community must strive to coordinate better.