Space Physics Seminar spring-2015

The solar dynamo and plasma convection produce three main observed structures extending from the solar surface into the corona – active regions, solar filaments (prominences when observed at the limb) and coronal holes. Each of these three key features is interlinked with the other two in its evolution and dynamics. Active regions can form clusters of magnetic activity and sunspots. When active regions decay, solar filaments form at their boundaries separating opposite magnetic polarities (neutral lines). Alternatively, decaying active regions in the presence of flux imbalance can give birth to lower latitude coronal holes. Accumulation of magnetic flux at coronal hole boundaries also creates the conditions for filament formation. Polar crown filaments are permanently present at the boundaries of the polar coronal holes. Middle-latitude and equatorial coronal holes - the result of active region evolution - can create pseudostreamers if other coronal holes of the same polarity are present. The pseudostreamer base at photospheric heights is multipolar; often one observes tripolar magnetic configurations with two neutral lines - where filaments can form - separating the coronal holes. There is debate as to the speed and nature of the wind from pseudostreamers: it could be fast, slow, or in between. I will demonstrate how the resulting wind type depends on the presence or absence of filaments at the pseudostreamer base. I will discuss mechanisms of formation and evolution for solar filaments and pseudostreamers, and the role active regions play in these processes.