Comprehensive Analysis of a Filament-embedding Solar Active Region at Different Stages of Evolution

Abstract

Active regions are the brightest structures seen in the solar corona, so their physical properties hold important clues to the physical mechanisms underlying coronal heating. In this work, we present a comprehensive study for a filament-embedding active region as determined from observations from multiple facilities including the Chinese H α Solar Explorer. We find three types of dynamic features that correspond to different thermal and magnetic properties, i.e., the overlying loops—1 MK cool loops, the moss region—2–3 MK hot loops’ footprints, and the sigmoidal filament. The overlying cool loops, which have a potential field, always show Doppler blueshifts at the east footprint and Doppler redshifts at the west, indicating a pattern of “siphon flow.” The moss-brightening regions, which sustain the hot loops that have a moderate sheared field, always show downward Doppler redshifts at the chromosphere, which could be a signature of plasma condensing into the inner region adjacent to the filament. The sigmoidal filament, which has strongly sheared field lines along the polarity inversion line, however, shows a different Doppler velocity pattern in its middle part, i.e., an upward Doppler blueshift at the double- J -shaped stage indicating tether-cutting reconnection during the filament channel formation and then a downward redshift showing the plasma condensation for the sigmoidal filament formation. The present work shows overall properties of the filament-embedding active region, constraining the heating mechanisms of different parts of the active region and providing hints regarding the mass loading of the embedded filament.

Keywords

• Solar activity
• Solar chromosphere
• Solar filaments
• Solar magnetic fields