A statistical comparison between HMI vector magnetograms and line-of-sight–derived radial fields shows that LOS-based estimates systematically underestimate the true radial field, with the bias increasing toward the limb. A numerical modeling demonstrate that this center-to-limb variation in the underestimation of radial field arises from non-radial magnetic field inclinations.
A robust, calibrated method for measuring sunspot areas from SOHO/MDI and SDO/HMI full-disk images enables a consistent, observer-independent, long-term catalogue of daily sunspot areas, revealing detailed patterns of sunspot group area evolution and solar cycle variability.
Through MHD simulations of flux eruptions, the study finds that the current helicity decreases prior to eruptions and then reverses to increase afterward. By examining multiple flare events, the authors identified observational evidence supporting these simulation results.
Multiple X-class flares and CMEs were produced by AR 13664/8 during the Mother’s Day week of 2024. This study suggests that predicting the locations of magnetically complex active regions, and studying and tracking their eruptive states using different proxy parameters can greatly improve the capability to forecast intense storms.
Each solar active region (AR) has its unique shape, size, and lifetime. In this work, the authors developed a method to ‘average’ bipolar ARs by normalizing their size, orientation, and timing, thereby revealing the typical properties of an AR and its evolutionary pattern.
It is widely known that magnetic fields suppress convection, but this effect has not been quantitatively assessed. Using vector magnetograms from HMI observations, the authors measured the advection speeds of magnetic flux as a function of field strength and found that the speeds steadily decrease with increasing field strength.
Eruptive and non-eruptive solar flares were investigated based on an analysis of electric current neutralization and torus instability. Combined analysis of these factors offers a more reliable prediction of eruptive events than relying on either one alone.
The analysis of magnetic fields and electrical currents indicates that a specific configuration – currents in opposite magnetic regions flowing in the same direction and peaking concurrently – might create favorable conditions for the magnetic reconnection process that powers solar flares.
Moreton waves were studied using a systematic survey of Moreton-wave events observed during the SDO era. The results showed that inclined magnetic configurations act as a wall, forcing eruptions and Moreton waves to propagate toward weaker magnetic fields.
A few major geoeffective flares and CMEs occurred in May 2024. HMI magnetic field data were used to examine how the flares occurred and why they became geoeffective.