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Aims . We aim to reproduce the structure of the corona above a solar active region as seen in the extreme ultraviolet (EUV) using a three-dimensional magnetohydrodynamic (3D MHD) model. Methods . The 3D MHD data-driven model solves the induction equation and the mass, momentum, and energy balance. To drive the system, we feed the observed evolution of the magnetic field in the photosphere of the active region AR 12139 into the bottom boundary. This creates a hot corona above the cool photosphere in a self-consistent way. We synthesize the coronal EUV emission from the densities and temperatures in the model and compare this to the actual coronal observations. Results . We are able to reproduce the overall appearance and key features of the corona in this active region on a qualitative level. The model shows long loops, fan loops, compact loops, and diffuse emission forming at the same locations and at similar times as in the observation. Furthermore, the low-intensity contrast of the model loops in EUV matches the observations. Conclusions . In our model the energy input into the corona is similar as in the scenarios of fieldline-braiding or flux-tube tectonics, that is, energy is transported to the corona through the driving of the vertical magnetic field by horizontal photospheric motions. The success of our model shows the central role that this process plays for the structure, dynamics, and heating of the corona.
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This content will become publicly available on July 16, 2026
Steady-state Heating of Diffuse Coronal Plasma in a Solar Active Region
Abstract The solar corona is much hotter than lower layers of the solar atmosphere—the photosphere and chromosphere. The coronal temperature is up to 1 MK in quiet Sun areas, while up to several megakelvins in active regions, which implies a key role of the magnetic field in coronal heating. This means that understanding coronal heating requires reliable modeling of the underlying 3D magnetic structure of an active region validated by observations. Here, we employ synergy between 3D modeling, optically thick gyroresonant microwave emission, and optically thin EUV emission to (i) obtain and validate the best magnetothermal model of the active region and (ii) disentangle various components of the EUV emission known as diffuse component, bright loops, open-field regions, and “moss” component produced at the transition region. Surprisingly, the best thermal model corresponds to high-frequency energy release episodes, similar to a steady-state heating. Our analysis did not reveal significant deviations of the elemental abundances from the standard coronal values.
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- PAR ID:
- 10627163
- Publisher / Repository:
- American Astronomical Society
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 988
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 100
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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