By analyzing resolved solar observations, we reveal significant temporal evolution in white-light flare area and temperature. Based on these findings, our new energy estimation method systematically yields lower flare energies, prompting a re-examination of classical macroscopic scaling laws.
Persistent magnetic flux emergence with perpendicular separation directions in AR 13842 rapidly formed a collisional shearing PIL, with frequent flux cancellations there, leading to repeated magnetic flux rope formations and multiple large flares. The pre-flare decreases in the sheared PIL’ s area and free-energy density may serve as a promising precursor for major eruptive flares.
Using SDO/HMI white-light continuum observations and GOES Lyα and SXR irradiance, this study investigates 69 solar white-light flares to examine their emission properties, including enhancement, peak-time ordering, evolutionary timescales, and relationships between the emission parameters and radiated energy.
Using 14 years of helioseismic and magnetic-field observations, this study shows that deeper subsurface outflows from active regions play an important role in transporting magnetic fluxes to the polar regions and regulating polar-field formation.
Spatiotemporal images of solar magnetic fluxes, made using the near-side magnetic-field observations and helioseismic far-side images, are analyzed separately using flux integration and power-spectrum analysis. Both results are consistent and imply that the surface active regions’ clustering patterns are likely imprints of magneto-Rossby waves in the tachocline.
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.
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.
Helioseismic analysis of solar torsional oscillations reveals dynamo-wave–like signatures that originate near the tachocline and propagate through the convection zone, linking internal zonal flows to the surface magnetic cycle. Additional evidence from frequency-splitting coefficients and rotational shear variations shows strong solar-cycle correlations, supporting the tachocline as a primary site of solar dynamo action.
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.
Equatorial Rossby waves at different depths are studied, and it is found that the Rossby waves are tilted retrograde with depth rather than being a columnar structure. The tilt remains relatively stable through the solar cycle without being consistently modulated by magnetic activity.