ApJL (Astrophysical Journal Letters): In May 2024, the strongest geomagnetic storm since 2003 hit Earth, peaking with a disturbance index of -412 nT. This storm was triggered by solar activity from solar Active Region (AR) 13664, which produced numerous powerful bursts of energy, including 12 X-class solar flares. Starting around May 7, AR 13664 rapidly grew in size and magnetic energy, sparking intense flare activity.
To better understand how this active region evolved and what led to these major solar eruptions, we used advanced 3D models to analyze the Sun’s magnetic fields. Specifically, we applied the NF2 model, which uses Artificial Intelligence (AI) to integrate physical equations with observational data from the Solar Dynamics Observatory (SDO). This approach allowed us to follow the active region’s magnetic changes in real time, from May 5 through May 11.
Our results show that drops in free magnetic energy coincide with large solar flares, and that all modeled X-class flares were associated with a sudden decrease in magnetic energy. A detailed look at the largest flare on May 10, an X3.9-class event, suggests that the flare resulted from the interaction between separated magnetic domains.
This study provides a detailed record of the magnetic field evolution of AR 13664, now publicly available for further research.
Magnetic field configuration and parameters prior to the X3.9 solar flare and associated filament eruption, as derived from a pre-flare non-linear force-free coronal magnetic field extrapolation on 2024 May 10-05:58:43 UT. Selected magnetic field structures, showing the filament channel colored by the local current density, a fan-spine structure in green, and overlying fields connecting both ribbons in gray.