An unsupervised machine-learning algorithm is used on selected features derived from the polarity inversion lines (PIL) mask and difference PIL mask. It is found these features are effective in predicting flaring occurrences.
The Sun’s poloidal and toroidal magnetic field components derived from synoptic magnetograms are assimilated into a mean-field dynamo model, and activity level for Cycle 25 is predicted based on this approach.
Electric current neutralization, which measures the ratio of direct current and return current inside active regions (ARs), is studied for a total of 30 AR samples. It is found that flare-productive ARs are more likely to exhibit non-neutralized currents than those flare-quiet ARs.
This study explores the magnetic triggers of recurrent active region jets. Both widely debated triggers, namely, flux cancellation and flux emergence, are associated alternatively to the apparently homologous jets.
Of three consecutive flares that occurred in a same active region within 4 hours, why were two non-eruptive and one eruptive? Non-linear force-free modeling suggest that breakout reconnection during the first two flares weakened the overlying field, allowing the flux rope to erupt in the third.
In an MHD simulation of flux emergence, a δ-sunspot is formed spontaneously by a collision of areas with opposite polarities. Driven by convective flows and counter-streaming flows, sheared polarity inversion lines form and flux ropes are created above.
Features of the Shannon entropy transfer between solar magnetic modes are described and analyzed. It is confirmed that solar magnetic modes can be separated into three groups: entropy sources, entropy transmitters, and entropy targets.
Photospheric magnetic properties for a set of coronal holes are investigated using HMI magnetograms, and it is found that the overall unbalanced magnetic flux of the coronal holes arises from long-lived magnetic elements with a lifetime longer than 40 hours.
A novel approach is developed to reconstruct the surface magnetic helicity density for the Sun or sun-like stars. The method is applied on the SDO/HMI-observed vector field synoptic data to study the temporal evolution of the Sun’s magnetic helicity density during Solar Cycle 24.
An algorithm, which is to calculate the electric field in order to retrieve the time variations of solar surface magnetic field observed by HMI, was recently developed.