Using Potential Field Extrapolations to Explore the Origin of Type II Spicules

We used 29 high resolution line of sight magnetograms (LOS) acquired with the Goode Solar Telescope (GST) in a quiet Sun area to extrapolate a series of potential field configurations and study their time variations. The analysis showed that there are regions that consistently exhibit changes in loop connectivity, while other vast areas do not show such changes. Analysis of topological features of the potential fields indicates that the photospheric footprint of the separatix between open and closed loop systems well matches the roots of rapid blue and red shifted excursions (RBEs/RREs), which are disk counterparts of type II spicules. The data showed that the footpoints of the observed ha features coincide with the footpoints of the loops that most frequently change their connectivity, and the area occupied by the open fields that did not show any significant and persistent connectivity changes is also void of prominent jet and spicular activity. We also detected and tracked magnetic elements using Southwest Automatic Magnetic Identification Suite and GST magnetograms, which allowed us to construct artificial magnetograms and calculate the corresponding potential field configurations. Analysis of the artificial data showed tendencies to those found for the observed data. The present study suggests that significant amount of chromospheric activity observed in far wings of the ha spectral line may be generated via reconnection between closed loop systems and the canopy fields consisting of “open” field lines.