Spectropolarimetric observations of an arch filament system with the GREGOR solar telescope

DOI: 
10.1002/asna.201612432
Publication date: 
01/11/2016
Main author: 
Balthasar H.
IAA authors: 
Orozco Suárez, D.
Authors: 
Balthasar H., Gömöry P., González Manrique S., Kuckein C., Kavka J., Kučera A., Schwartz P., Vašková R., Berkefeld T., Collados Vera M., Denker C., Feller A., Hofmann A., Lagg A., Nicklas H., Orozco Suárez D., Pastor Yabar A., Rezaei R., Schlichenmaier R., Schmidt D., Schmidt W., Sigwarth M., Sobotka M., Solanki S.K., Soltau D., Staude J., Strassmeier K.G., Volkmer R., von der Lühe O., Waldmann T.
Journal: 
Astronomische Nachrichten
Refereed: 
Yes
Publication type: 
Article
Volume: 
337
Pages: 
1050-1056
Number: 
Abstract: 
Arch filament systems occur in active sunspot groups, where a fibril structure connects areas of opposite magnetic polarity, in contrast to active region filaments that follow the polarity inversion line. We used the GREGOR Infrared Spectrograph (GRIS) to obtain the full Stokes vector in the spectral lines Si I λ 1082.7 nm, He I λ 1083.0 nm, and Ca I λ 1083.9 nm. We focus on the near-infrared calcium line to investigate the photospheric magnetic field and velocities, and use the line core intensities and velocities of the helium line to study the chromospheric plasma. The individual fibrils of the arch filament system connect the sunspot with patches of magnetic polarity opposite to that of the spot. These patches do not necessarily coincide with pores, where the magnetic field is strongest. Instead, areas are preferred not far from the polarity inversion line. These areas exhibit photospheric downflows of moderate velocity, but significantly higher downflows of up to 30 km s–1 in the chromospheric helium line. Our findings can be explained with new emerging flux where the matter flows downward along the field lines of rising flux tubes, in agreement with earlier results. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim). Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Database: 
SCOPUS
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2016AN....337.1050B/abstract
ADS Bibcode: 
2016AN....337.1050B
Keywords: 
Sun: filaments; Sun: photosphere; techniques: polarimetric; techniques: spectroscopic