Revisiting the Role of Global Magnetic Variables in Coronal Heating of Solar Active Regions
Abstract
Reconnection-based models of coronal heating predict that magnetic complexity---non-potential configurations, currents, shear---should enhance coronal emission independently of total magnetic flux. Previous work, however, found no evidence that complexity contributes independently to coronal heating (Fisher et al. 1998). We revisit this question using SDO/HMI vector magnetograms and SDO/AIA EUV imaging. HMI Space-weather Active Region Patches (SHARPs) provide 16 magnetic parameters characterizing field strength, gradients, currents, helicity, and non-potentiality. We measure spatially-integrated transition region and coronal emission using AIA 304A, 193A, 94A, and isolated Fe XVIII emission for 137 active regions, sampling plasma at ~0.09MK, ~1.4MK, and ~7.1MK. Partial correlation analysis isolates the contribution of each complexity parameter after controlling for total unsigned vertical magnetic flux. Unsigned flux (Phi_M) explains 72--82\% of variance in emission, following power laws (I ~ Phi_M^alpha, where alpha=0.61-1.19) consistent with prior soft X-ray results. Partial correlations reveal weak positive contributions (r = 0.2-0.3) to transition region (304A) emission from some vertical current and field parameters, but little evidence that other active-region-averaged measures of magnetic complexity enhance coronal emission. The exception is total photospheric magnetic free energy density (rho_tot), which shows a positive partial correlation (r = 0.49, p < 0.001) with Fe XVIII emission, but negative, or non-existent, partial correlations with other AIA filters. These results suggest quasi-steady coronal heating scales with magnetic flux, while rho_tot may contribute to high temperature coronal heating. At lower temperatures, regions with more stored energy than expected for their flux produce less EUV emission than expected.
Related
- Three-dimensional magnetic reconnection in unipolar regions. A case study of coronal bright points in the Sun
- Understanding how Coronal Heating and Magnetic Field Scaling Affect Global Properties of the Low and Middle Corona
- Heating of Solar Coronal Loops by Converging Unipolar Magnetic Flux: Evidence from SDO Observations and a Radiative MHD Simulation
- Three-dimensional magnetic reconnection in unipolar regions. A case study of coronal bright points in the Sun
- Influence of numerical domain design in simulations of solar coronal heating with the MAGEC code
BibTeX
@misc{brooks2026revisiting,
title = {{Revisiting the Role of Global Magnetic Variables in Coronal Heating of Solar Active Regions}},
author = {David H. Brooks and Harry P. Warren and Johnathan R. Stauffer},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.17972},
eprint = {2610.17972},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.17972},
}
RIS
TY - UNPB
TI - Revisiting the Role of Global Magnetic Variables in Coronal Heating of Solar Active Regions
AU - David H. Brooks
AU - Harry P. Warren
AU - Johnathan R. Stauffer
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.17972
UR - https://arxiv.org/abs/2610.17972
AB - Reconnection-based models of coronal heating predict that magnetic complexity---non-potential configurations, currents, shear---should enhance coronal emission independently of total magnetic flux. Previous work, however, found no evidence that complexity contributes independently to coronal heating (Fisher et al. 1998). We revisit this question using SDO/HMI vector magnetograms and SDO/AIA EUV imaging. HMI Space-weather Active Region Patches (SHARPs) provide 16 magnetic parameters characterizing field strength, gradients, currents, helicity, and non-potentiality. We measure spatially-integrated transition region and coronal emission using AIA 304A, 193A, 94A, and isolated Fe XVIII emission for 137 active regions, sampling plasma at ~0.09MK, ~1.4MK, and ~7.1MK. Partial correlation analysis isolates the contribution of each complexity parameter after controlling for total unsigned vertical magnetic flux. Unsigned flux (Phi_M) explains 72--82\% of variance in emission, following power laws (I ~ Phi_M^alpha, where alpha=0.61-1.19) consistent with prior soft X-ray results. Partial correlations reveal weak positive contributions (r = 0.2-0.3) to transition region (304A) emission from some vertical current and field parameters, but little evidence that other active-region-averaged measures of magnetic complexity enhance coronal emission. The exception is total photospheric magnetic free energy density (rho_tot), which shows a positive partial correlation (r = 0.49, p < 0.001) with Fe XVIII emission, but negative, or non-existent, partial correlations with other AIA filters. These results suggest quasi-steady coronal heating scales with magnetic flux, while rho_tot may contribute to high temperature coronal heating. At lower temperatures, regions with more stored energy than expected for their flux produce less EUV emission than expected.
ER -