# New Evidence that Magnetoconvection Drives Solar-Stellar Coronal Heating

## TL;DR

This study provides new evidence that magnetoconvection is a key driver of coronal heating in the Sun and stars, showing how magnetic field strength at loop footpoints influences heating efficiency.

## Contribution

It demonstrates that strong umbral magnetic fields suppress magnetoconvection, revealing a mechanism for coronal heating regulation based on magnetic field configurations.

## Key findings

- Umbra-to-umbra coronal loops are invisible despite strong magnetic flux.
- Brightest loops connect different sunspot regions or plage areas.
- Strong umbral fields at both ends inhibit magnetoconvection and heating.

## Abstract

How magnetic energy is injected and released in the solar corona, keeping it heated to several million degrees, remains elusive. Coronal heating generally increases with increasing magnetic field strength. From comparison of a non-linear force-free model of the three-dimensional active-region coronal field to observed extreme-ultraviolet loops, we find that (1) umbra-to-umbra coronal loops, despite being rooted in the strongest magnetic flux, are invisible, and (2) the brightest loops have one foot in an umbra or penumbra and the other foot in another sunspot's penumbra or in unipolar or mixed-polarity plage. The invisibility of umbra-to-umbra loops is new evidence that magnetoconvection drives solar-stellar coronal heating: evidently the strong umbral field at \underline{both} ends quenches the magnetoconvection and hence the heating. Broadly, our results indicate that, depending on the field strength in both feet, the photospheric feet of a coronal loop on any convective star can either engender or quench coronal heating in the loop's body.