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 new analysis using about 4 years of HMI 5-min solar p-mode limb oscillations as a rotation “tracer” finds a large velocity gradient at the top of the photosphere. It is suggested that the net effect of the photospheric angular momentum loss is similar to Poynting-Robertson “photon braking” on, for example, Sun-orbiting dust.
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 authors introduce a new Python module that can be used to access the HMI and AIA data provided by the JSOC.
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.
Through mimicking observations in high-latitude areas, we find that the foreshortening affects the time-distance measured mean travel-times, but is not accountable for the center-to-limb effect in travel-time differences.
We have generated a dataset of emerging active regions (EARs) observed by SDO/HMI that is specifically suitable for helioseismic analysis. Using this dataset we show that, on average the bipoles have a symmetric the east-west velocity relative to differential rotation.
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.