Spectropolarimetric observations of an arch filament system with the GREGOR solar telescope
| Autor: | T. Waldmann, Reza Rezaei, Thomas Berkefeld, J. Kavka, Klaus G. Strassmeier, Harald Nicklas, Axel Hofmann, D. Orozco Suárez, M. Collados Vera, R. Vasková, W. Schmidt, Michael Sigwarth, Peter Gömöry, Carsten Denker, Andreas Lagg, Alex Feller, Michal Sobotka, O. von der Lühe, S. J. González Manrique, Christoph Kuckein, P. Schwartz, Sami K. Solanki, Rolf Schlichenmaier, A. Pastor Yabar, A. Kučera, D. Soltau, H. Balthasar, Dirk Schmidt, Reiner Volkmer, J. Staude |
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| Rok vydání: | 2016 |
| Předmět: |
Physics
Photosphere Sunspot 010504 meteorology & atmospheric sciences Polarity (physics) Flux Astronomy and Astrophysics Astrophysics 01 natural sciences Spectral line Magnetic field Protein filament 13. Climate action Space and Planetary Science 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics 010303 astronomy & astrophysics 0105 earth and related environmental sciences Line (formation) |
| Zdroj: | Astronomische Nachrichten. 337:1050-1056 |
| ISSN: | 0004-6337 |
| DOI: | 10.1002/asna.201612432 |
| Popis: | 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 1082.7 nm, He I 1083.0 nm, and Ca I 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 in the chromospheric helium line. Our findings can be explained with new emerging flux where the matter flows downward along the fieldlines of rising flux tubes, in agreement with earlier results. |
| Databáze: | OpenAIRE |
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