Response of the Corona to Magnetic Activity in Underlying Plage Regions

Abstract

The fact that corona is strongly inhomogeneous in space and evolves in time in very different ways means that the processes of energy production, flow, and release have several branches. The processes of the extraction of energy stored in the photosphere, strongly depend on the magnetic filling factor, i.e., whether we deal with the quiet sun network, plages, or active regions. So far we were studying rarefied ensembles of flux tubes typical to quiet sun. In this chapter, we move to denser ensembles of flux tubes typical to plages and consider the response of the upper atmosphere to magnetic activity in underlying plage regions. We will see that the character of the EUV emission above plage regions that are dominated by single polarity magnetic elements, i.e., unipolar plages, always has an amorphous shape that topologically mimics the shape of the underlying plage. Contrary to this, the EUV emission above mixed polarity plages is highly discrete and consists of sporadic localized radiative transients. Such a different response of the chromosphere/corona to unipolar and mixed polarity plages obviously implies the action of different mechanisms for energy production, flow, and release. In all cases, however, the primary energy source lies in continuous hydromagnetic activity among the photospheric magnetic fields. It is just the character of this activity, different in differently magnetized regions, that determines the processes of the extraction of energy and its transport throughout the solar atmosphere.