Apparent 3-min waves observed inside sunspot umbrae are modeled as excited about 1000 to 2000 km beneath sunspots’ surface.
A statistical study of sunspot region properties yields insights on why some are flare-productive.
A comparison of the surface flow patterns in observation and numerical simulation suggests that the flux tube emerging speed has been overestimated in theories.
The F10.7 microwave flux shows remarkabke agreement with the unsigned magnetic flux from MDI and HMI over the past 20 years, attesting to the accuracy and significance of both.
Tiny sunspots, or pores, might have escaped the observers during the Maunder minimum. However, they might have carried enough magnetic flux for the normal operation of a Babcock-Leighton-type dynamo.
Omnipresent magneto-acoustic waves, originating from within the underlying sunspot and propagating radially outwards, allow the spatial variation of the local coronal magnetic field to be mapped with high precision.