Fine structure in an active region

With the waning 24th sunspot cycle, only few active regions and sunspots appear on the solar surface. Magnetic fields which currently reach the solar surface only produce small pores, which prevail for a few days before they disappear. A region of emerging flux with a few pores was observed on May 24, 2017, with the broad band imager (BBI) at the 1.5m GREGOR solar telescope on Tenerife. The BBI observes the solar surface with two cameras simultaneously, with highest spatial and time resolution, in several regions of the solar spectrum.

The two images show a pore at 10:52 collected with a time lag of only 26 seconds. One image was taken in the spectral continuum at 656 nm, in the vicinity of the famous Balmer Alpha absorption line of Hydrogen. The second image shows the same region through a narrow-band filter centered on a strong absorption line of calcium at 854 nm. Here, the radiation originates from a higher layer in the solar atmosphere where small magnetic elements are prominently visible in the form of “faculae”. The upwelling magnetic field has a strong influence on the appearance of granulation. Time series of such observations permit studying the local influence of magnetic fields on the morphology and dynamics of solar convection.