Magnetic flux systems involved in the May 2024 solar energetic events from AR 13664 inferred through coronal dimmings
Amaia Razquin, Karin Dissauer, Astrid M. Veronig, Graham Barnes
arXiv:2603.23623v1 Announce Type: new
Abstract: Coronal dimmings are transient depletions of coronal plasma observed in extreme ultraviolet and soft X-rays, interpreted as low-corona signatures of coronal mass ejections (CMEs). Their evolution is closely linked to CME dynamics, flare reconnection, and large-scale coronal magnetic restructuring. In May 2024, active region (AR) 13664 produced 66 > M-class flares and multiple fast CMEs that caused the strongest geomagnetic storm since 2003. We analysed 16 on-disc dimmings observed in SDO/AIA 211AA data between May 1-14, 2024. We extracted dimmings using logarithmic base-ratio thresholding, and derived magnetic properties from SDO/HMI line-of-sight magnetograms. We identified flare ribbons in AIA 1600AA data via adaptive thresholding, and computed reconnection fluxes from radial magnetic field maps. We examined the magnetic flux systems involved in the eruptions using PFSS and NLFF extrapolations. We found correlations between dimming and flare ribbon properties stronger than previously reported. The dimming morphology evolved systematically, with southward expansion before May 9 and northward afterward, coinciding with a shift in flare ribbon locations between two mayor east-west polarity inversion lines (PILs). These changes imply the presence of two distinct magnetic domains. The PFSS extrapolations showed that southward (northward) dimmings are mainly strapping flux dimmings with magnetic field lines vaulting above the southern (northern) PIL. The final extent of the dimmings was then given by the exterior flux involved in the eruption via stretching and reconnection. One event revealed an extended quiet-Sun dimming likely triggered by EUV wave-induced field opening.arXiv:2603.23623v1 Announce Type: new
Abstract: Coronal dimmings are transient depletions of coronal plasma observed in extreme ultraviolet and soft X-rays, interpreted as low-corona signatures of coronal mass ejections (CMEs). Their evolution is closely linked to CME dynamics, flare reconnection, and large-scale coronal magnetic restructuring. In May 2024, active region (AR) 13664 produced 66 > M-class flares and multiple fast CMEs that caused the strongest geomagnetic storm since 2003. We analysed 16 on-disc dimmings observed in SDO/AIA 211AA data between May 1-14, 2024. We extracted dimmings using logarithmic base-ratio thresholding, and derived magnetic properties from SDO/HMI line-of-sight magnetograms. We identified flare ribbons in AIA 1600AA data via adaptive thresholding, and computed reconnection fluxes from radial magnetic field maps. We examined the magnetic flux systems involved in the eruptions using PFSS and NLFF extrapolations. We found correlations between dimming and flare ribbon properties stronger than previously reported. The dimming morphology evolved systematically, with southward expansion before May 9 and northward afterward, coinciding with a shift in flare ribbon locations between two mayor east-west polarity inversion lines (PILs). These changes imply the presence of two distinct magnetic domains. The PFSS extrapolations showed that southward (northward) dimmings are mainly strapping flux dimmings with magnetic field lines vaulting above the southern (northern) PIL. The final extent of the dimmings was then given by the exterior flux involved in the eruption via stretching and reconnection. One event revealed an extended quiet-Sun dimming likely triggered by EUV wave-induced field opening.

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