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.
Compactness is one geometric property of a sunspot group that has not yet been systematically quantified. We calculate the compactness of a small sample of δ-spots and β-spots using a minimum bounding circle. On average, the δ-spots are found to be more than twice as compact as the β-spots.
Another white-light flare was captured by HMI off the solar limb, this time with materials seen ejected from the Sun. A fraction of the ejecta was seen falling back to the Sun.
An unprecedented observation of a limb flare in HMI’s white-light continuum shows that the white-light intensity at the post-flare loop-top continues to grow for 16 more minutes while UV/EUV intensities decay. Both the WL/UV intensity and the EUV intensities show quasi-periodic pulsations with a period close to 8.0 and 6.8 minutes, respectively.
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.
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.
AR12192, the largest active region in Solar Cycle 24, produced 6 X-class flares, but none of them were associated with a CME. However, a much weaker flare, of M4.0-class, was associated with a CME. Magnetic field and morphological changes are analyzed during these flares to understand why this is the case.
44 strong flares are analyzed, and a few factors are identified to determine whether a flare will be eruptive or confined.
Magnetic field changes associated with solar flares, observed by the SDO/HMI, are surveyed, and permanent changes of magnetic field are found in the majority of flare events. Properties of the magnetic field changes are further investigated.