A statistical investigation of the background magnetic field decay index reveals interesting features of the critical height for the flux rope torus instability.
We quantify the emergence and decay rates of ten bipolar active regions using vector magnetic field data from HMI. Our results, placed in context with other observational and modeling results in the literature, confirm a trend that higher flux regions emerge faster and the rate is dependent on the total flux of that region.
A new method tracking individual features in a long time series of magnetograms yields new measurements of solar differential rotation and meridional circulation rate.
Rapid and irreversible changes in chromospheric magnetic field during a flare have been observed for the first time. They look surprisingly different from their photospheric counterpart.
New HMI high-cadence vector magnetograms are now available. Observations every 135 or 90 seconds reveal the rapid magnetic evolution occurring during major solar eruptions.
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.
Through analyzing a suite of space- and ground-based observations, the authors report that above sunspots, helioseismic waves of different frequencies are able to channel up through the chromosphere and transition region into corona. General pictures of how the waves make into corona are also shown.
HMI now routinely produces vector magnetic field synoptic charts. This Nugget describes the data reduction procedures and the method chosen to resolve the 180-degree ambiguity in azimuth.
Using a combination of the magnetograms, we find signs of the beginning of the 25th cycle from both HMI and WSO by calculating the inclination angles determined from the variation in line of sight field during a disk passage.