IRIS Movie of the Day
At least once a week a movie of the Sun taken by NASA's Interface Region Imaging Spectrograph (IRIS) is posted by one of the scientists operating the instrument.
Granulation observed with IRIS at 283.2 nm
Credit: IRIS, LMSAL/NASA, Thierry Roudier
IRIS was designed to observe the Solar chromosphere and transition region; the part of the solar atmosphere between the surface, the photosphere, and the hot corona. An exception is found when looking far into the wings of the Mg II h and k spectral lines, where the photosphere can be observed as well, as shown in this movie. There we see granulation, the result of heat ???bubbling up??? from the solar interior. It is these convective motions that drive the heating of the outer layers, the chromosphere, transition region, and corona, as acoustic waves are launched, and perhaps more importantly, as the magnetic field is shuffled around. The imprint of the magnetic field is seen in the small bright points in this movie that are shoved around by granular flows. The magnetic field lines are connected to the outer atmosphere and as they are perturbed and moved the field lines will either reconnect when they intercept each other, or host magnetic waves; both phenomena cause heating and the energization of the chromosphere and regions above. By combining such views with events in the chromosphere, seen for example in the core of the Mg II h and k lines observed by IRIS, a deeper understanding of the outer solar atmosphere can be attained.