Unveiling key factors in solar eruptions leading to the solar superstorm in 2024 May

NOAA active region (AR) 13664/8 produced the most intense geomagnetic effects since the Halloween event of 2003. The resulting extreme solar storm is thought to be the consequence of multiple interacting coronal mass ejections (CMEs). Notably, this AR exhibits exceptionally rapid magnetic flux emergence. The eruptions on which we focus all occurred along collisional polarity inversion lines (PILs) through collisional shearing during a three-day period of extraordinarily high flux emergence (∼10 21 Mx h −1 ). Our key findings reveal how photospheric magnetic configurations in eruption sources influence solar superstorm formation and geomagnetic responses, and link exceptionally strong flux emergence to sequential homologous eruptions: (1) We identified the source regions of seven halo CMEs that were distributed primarily along two distinct PILs. This distribution suggests two groups of homologous CMEs. (2) The variations in the magnetic flux emergence rates in the source regions are correlated with the CME intensities. This might explain the two contrasting cases of complex ejecta that are observed at Earth. (3) Our calculations of the magnetic field gradients around the CME source regions show strong correlations with eruptions. This provides crucial insights into solar eruption mechanisms and enhances our prediction capabilities for future events.