Both magnetic flux emergence and shearing flows occurred before the X9.3 flare on 2017 September 6. This analysis shows that shearing flows played a more significant role in leading to the helicity and electric currents buildup before the major eruption.
An analysis of zonal flow acceleration/deceleration inside the Sun reveals patterns of dynamo waves, and suggests that the primary seat of the dynamo is located in a high-latitude zone of the tachocline.
Observations of 10 coronal jetlets show that flux cancelation is usually a necessary condition for buildup and triggering of UV/EUV coronal network jetlets, and that network jetlets are plausibly small-scale versions of larger coronal jets.
A strong limb flare observed simultaneously by the SDO/AIA and SDO/HMI, which is very rare, allows the authors to study the emission mechanism for white-light flare loops, as well as estimate the electron densities along the flare loop.
A total of 90 circular-ribbon flares are identified in 8 years of SDO observations, and 33 of them are found associated with white-light enhancements, a rate higher than non-circular-ribbon flares. It is thus suggested that the fan-spine magnetic field topology and the total amount of energy release plays roles in causing white-light flares.
Physical parameters, including sunspots tilt angles, total magnetic flux, polarity pole separations, and magnetic areas, are measured for most sunspot groups in solar cycles 23 and 24. Differences between Hale and anti-Hale sunspots in separate hemispheres and cycles are studied statistically.
Jets resulting from eruption of minifilaments have lots of similarities to CMEs resulting from eruptions of large-scale filaments. This study on occurrences of jets can shed light on our understanding of what causes CME eruptions.
Through simulations using Babcock-Leighton flux transport model, it is found that the abrupt changes on the polar field near solar minimum could be the cause of the sunspot number double peaks in the next solar cycle.
Synoptic Q-maps, which display a geometric parameter describing the squashing factor of elemental flux tubes, are computed using both HMI and MDI magnetic field observations. These maps are useful for understanding coronal configurations relevant to space weather.
Analysis of HMI and KONUS/WIND data shows that photospheric and helioseismic flare impacts started to develop in compact regions in close vicinity of the magnetic polarity inversion line in the pre-impulsive phase before detection of hard X-ray emission.