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| Main Authors: | , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2510.27024 |
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| _version_ | 1866918274727411712 |
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| author | Kazachenko, Maria D. Fan, Yuhong Afanasyev, Andrey N. |
| author_facet | Kazachenko, Maria D. Fan, Yuhong Afanasyev, Andrey N. |
| contents | Understanding the three-dimensional evolution of coronal magnetic fields during solar flares remains challenging due to the lack of direct coronal field measurements. Here we combine data-driven MHD simulations of NOAA AR 11158 (Fan et al., 2024) with flare-ribbon and coronal-dimming observations to investigate realistic coronal magnetic-field evolution during an X-class flare. We introduce L-maps - maps of natural logarithm of magnetic field-line lengths - as a diagnostic tool to track the dynamics of simulated coronal magnetic structures. Variations in L-maps identify flare ribbons through field-line shortening and coronal dimmings through field-line lengthening. Comparison with SDO/AIA observations demonstrates strong morphological and temporal agreement, validating the simulated field evolution. Applying K-means clustering to the L-map temporal profiles, we distinguish three stages of coronal evolution: (1) slow pre-flare rise phase, (2) flare reconnection accompanied by CME rise, and (3) post-reconnection CME expansion. We detect a slow pre-flare rise phase of magnetic field lines rooted in ribbon footpoints and identify reconnection dimming - area of rapid expansion of active-region core magnetic field lines during flare impulsive phase due to reconnection. Our results show that L-maps provide a powerful and physically intuitive framework for bridging simulations and observations and for tracking the full three-dimensional evolution of coronal magnetic fields during flares. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_27024 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | When Magnetic Field Lines Stretch, Snap, and Expand: A New Look at Solar Flares with L-maps Kazachenko, Maria D. Fan, Yuhong Afanasyev, Andrey N. Solar and Stellar Astrophysics Understanding the three-dimensional evolution of coronal magnetic fields during solar flares remains challenging due to the lack of direct coronal field measurements. Here we combine data-driven MHD simulations of NOAA AR 11158 (Fan et al., 2024) with flare-ribbon and coronal-dimming observations to investigate realistic coronal magnetic-field evolution during an X-class flare. We introduce L-maps - maps of natural logarithm of magnetic field-line lengths - as a diagnostic tool to track the dynamics of simulated coronal magnetic structures. Variations in L-maps identify flare ribbons through field-line shortening and coronal dimmings through field-line lengthening. Comparison with SDO/AIA observations demonstrates strong morphological and temporal agreement, validating the simulated field evolution. Applying K-means clustering to the L-map temporal profiles, we distinguish three stages of coronal evolution: (1) slow pre-flare rise phase, (2) flare reconnection accompanied by CME rise, and (3) post-reconnection CME expansion. We detect a slow pre-flare rise phase of magnetic field lines rooted in ribbon footpoints and identify reconnection dimming - area of rapid expansion of active-region core magnetic field lines during flare impulsive phase due to reconnection. Our results show that L-maps provide a powerful and physically intuitive framework for bridging simulations and observations and for tracking the full three-dimensional evolution of coronal magnetic fields during flares. |
| title | When Magnetic Field Lines Stretch, Snap, and Expand: A New Look at Solar Flares with L-maps |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2510.27024 |