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.
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 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.
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.
Large-scale inflows form around emerging solar active regions in the near-surface layer and alter the global meridional flow patterns.
We observed magnetoacoustic waves propagating along the magnetic field lines of a sunspot. Based on the wave periods and atmospheric characteristics, we reconstructed the magnetic field topology of the sunspot.
Multiple-wavelength high-resolution observations reveal running penumbral waves in the middle photosphere, with an apparent horizontal speed of up to 51 km/s.
A newly discovered, fast-moving wave propagates outward along sunspots’ radial direction and may provide new diagnostics of the sunspot subsurface structure.