Filigree in the Surroundings of Polar Crown and High-Latitude Filaments

Abstract

High-resolution observations of polar crown and high-latitude filaments are scarce. We present a unique sample of such filaments observed in high-resolution H$\alpha$ narrow-band filtergrams and broad-band images, which were obtained with a new fast camera system at the Vacuum Tower Telescope (VTT), Tenerife, Spain. The Chromospheric Telescope (ChroTel) provided full-disk context observations in H$\alpha$, Ca II K, and He I 10830 A. The Helioseismic and Magnetic Imager (HMI) and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) provided line-of-sight magnetograms and ultraviolet (UV) 1700 A filtergrams, respectively. We study filigree in the vicinity of polar crown and high-latitude filaments and relate their locations to magnetic concentrations at the filaments' footpoints. Bright points are a well studied phenomenon in the photosphere at low latitudes, but they were not yet studied in the quiet network close to the poles. We examine size, area, and eccentricity of bright points and find that their morphology is very similar to their counterparts at lower latitudes, but their sizes and areas are larger. Bright points at the footpoints of polar crown filaments are preferentially located at stronger magnetic flux concentrations, which are related to bright regions at the border of supergranules as observed in UV filtergrams. Examining the evolution of bright points on three consecutive days reveals that their amount increases while the filament decays, which indicates they impact the equilibrium of the cool plasma contained in filaments.

26 pages, 11 figures, 1 table, accepted for publication in Solar Physics

References in corpus (8)

• Magnetic properties of G-band bright points in a sunspot moat
• The GREGOR Fabry-Pérot Interferometer
• Real-time flare detection in ground-based H$\alpha$ imaging at Kanzelhöhe Observatory
• Vector magnetic fields of Solar Granulation
• Chromospheric Synoptic Maps of Polar Crown Filaments
• Calibration of full-disk He I 10830 Å filtergrams of the Chromospheric Telescope
• The polarization signature of photospheric magnetic fields in 3D MHD simulations and observations at disk center
• High-resolution spectroscopy of an erupting minifilament and its impact on the nearby chromosphere

Cited by in corpus (2)

• A Universal Method for Solar Filament Detection from H-alpha Observations using Semi-supervised Deep Learning
• Solar Spicules, Filigrees and Solar Wind Switchbacks