Monthly Archives: April 2026

225. Data-Driven Modeling Unveils the Magnetic “Sigmoid” Triggering a Major CME

Contributed by Sanjay Gosain. Posted on April 7, 2026

Magnetofrictional simulations of Active Region 13500 reproduce its transition from stability to eruption and show that a massive sigmoid flux rope formed during the decay phase. The eruption began when the current-carrying helicity ratio reached about 0.3, indicating that helicity-based markers can help diagnose the eruptive potential of active regions.

224. Moderate Nesting and Cross-Equatorial Asymmetry of Active Regions in Solar Cycle 24

Contributed by Aimee Norton. Posted on April 3, 2026

HMI data from Solar Cycle 24 data are used to determine how often the Sun emerges sunspots in activity nests. It is found that the Sun shows moderate nesting behavior with 41% (48%) of AR magnetic flux found in northern (southern) hemisphere located in nests. The maximum number of nests are found with slightly prograde rotational velocities, and the nesting behavior is asymmetric in the hemispheres.