Tracing magnetic flux rope footpoints in AR 12975 with coronal dimmings and data-driven magnetofrictional simulations
Abstract
Coronal mass ejections (CMEs) are driven by the eruption of magnetic flux ropes (MFRs) whose footpoints are often observed indirectly as coronal dimming regions. However, the relationship between observed dimmings and true MFR footpoint locations remains uncertain due to limitations in both detection methods and coronal magnetic field modelling caused by the complexity of eruptive events. We aim to investigate the M4 flare and CME event on 28 March 2022 in AR 12975 to determine how well observed coronal dimmings trace the footpoints of an erupting MFR. We also assess how these signatures compare with the MFR evolution from a data-driven magnetofrictional simulation. We combined multiwavelength SDO/AIA observations with a time-dependent data-driven magnetofrictional simulation of the AR. We identified coronal dimmings using intensity-thresholding and minimum-intensity maps. For challenging regions we used a tailored region growth algorithm from strong gradients. We extracted MFR structures in the simulation using a combined twist and squashing factor metric. We compared the location of the footpoints and derived magnetic fluxes from both dimmings and the modelled MFR. The simulation reproduces the formation, evolution, and eruption of the observed MFR whose footpoints migrate during the eruption. The footpoints match well with the dimming location. The southern dimming shows characteristics of a moving flux rope dimming, while the northern dimming behaves as a shrinking flux rope dimming that is rapidly closed by the flare ribbons. Quantitative comparisons of area and magnetic flux show good overall agreement between simulated footpoints and observed dimmings, with discrepancies mainly arising from detection limitations and event complexity. The dimmings at the northern footpoint region is particularly challenging in observations due to pre-existing low intensities and its fast shrinkage.
Versions
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BibTeX
@misc{wagner2026tracing,
title = {{Tracing magnetic flux rope footpoints in AR 12975 with coronal dimmings and data-driven magnetofrictional simulations}},
author = {Andreas Wagner and Amaia Razquin and Astrid M. Veronig and Emilia K. J. Kilpua and Karin Dissauer and Jens Pomoell},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.27521},
eprint = {2609.27521},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.27521},
}
RIS
TY - UNPB
TI - Tracing magnetic flux rope footpoints in AR 12975 with coronal dimmings and data-driven magnetofrictional simulations
AU - Andreas Wagner
AU - Amaia Razquin
AU - Astrid M. Veronig
AU - Emilia K. J. Kilpua
AU - Karin Dissauer
AU - Jens Pomoell
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.27521
UR - https://arxiv.org/abs/2609.27521
AB - Coronal mass ejections (CMEs) are driven by the eruption of magnetic flux ropes (MFRs) whose footpoints are often observed indirectly as coronal dimming regions. However, the relationship between observed dimmings and true MFR footpoint locations remains uncertain due to limitations in both detection methods and coronal magnetic field modelling caused by the complexity of eruptive events. We aim to investigate the M4 flare and CME event on 28 March 2022 in AR 12975 to determine how well observed coronal dimmings trace the footpoints of an erupting MFR. We also assess how these signatures compare with the MFR evolution from a data-driven magnetofrictional simulation. We combined multiwavelength SDO/AIA observations with a time-dependent data-driven magnetofrictional simulation of the AR. We identified coronal dimmings using intensity-thresholding and minimum-intensity maps. For challenging regions we used a tailored region growth algorithm from strong gradients. We extracted MFR structures in the simulation using a combined twist and squashing factor metric. We compared the location of the footpoints and derived magnetic fluxes from both dimmings and the modelled MFR. The simulation reproduces the formation, evolution, and eruption of the observed MFR whose footpoints migrate during the eruption. The footpoints match well with the dimming location. The southern dimming shows characteristics of a moving flux rope dimming, while the northern dimming behaves as a shrinking flux rope dimming that is rapidly closed by the flare ribbons. Quantitative comparisons of area and magnetic flux show good overall agreement between simulated footpoints and observed dimmings, with discrepancies mainly arising from detection limitations and event complexity. The dimmings at the northern footpoint region is particularly challenging in observations due to pre-existing low intensities and its fast shrinkage.
ER -