The Sun’s near surface shear layer (NSSL) is characterized by using HMI ring-diagram results. It is found the NSSL is composed of three distinct layers: a deeper larger region with a small shear, a narrow middle layer with a strong shear, and a layer very close to the surface.
A new method was developed to identify white-light flares (WLFs) observed in SDO/HMI continuum intensity. The new method is able to identify around 30% of C-class flares (and more percentage in stronger flares) having white light brightening associated with them, greatly expanding the total number of WLFs observed by HMI. The increased number of detections would help a statistical study of the properties of WLFs.
This study analyzes a few properties of evolving bipolar magnetic regions: separation of polarities, tilt angles, and tilt angle and flux relations. The analysis supports that the bipolar regions form from thin-flux tubes and Coriolis force plays an important role in forming the regions.
NOAA active regions 13664/8, the solar source region responsible for the May 2024 extreme geomagnetic disturbances that caused the largest geomagnetic storm since 2003, broke the record of magnetic flux emergence rate in the SDO era.
The advective flux transport model, coupled with a random active region generator, predicts that the solar activity will peak in the northern hemisphere around August 2024, and peak in the southern hemisphere around February 2025.
A spectro-polarimetric analysis of the sunquake sources observed during an X1.5 flare revealed transient emission in the FeI 6173Å line core, indicating intense, impulsive heating in the lower photosphere at the beginning of the flare impulsive phase.
A survey of how many off-limb white-light events were observed by the SDO/HMI was conducted, and a catalogue is published online with real-time updates.
Equatorial Rossby waves are detected using the HMI’s time-distance subsurface flow fields. It is also found that the power of the Rossby waves show a positive correlation with the sunspot number, while the frequency of the waves shows an anti-correlation with the sunspot number.
It is well known that many active regions (ARs) last longer than one solar rotation, however, they are often assigned one NOAA AR number for each rotation. This work lists most, if not all, of the ARs that are a same AR but with different AR numbers.
HMI magnetic field synoptic maps are used to evaluate the magnetic field structures’ organization and propagation as a function of time and latitude. It is demonstrated that the organization of longitudinal structures observed on synoptic maps is proportional to the level of activity at given latitudes.