Chromospheric filaments
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Magnetic topology of solar filaments
Vacuum Tower Telescope+Dutch Open
Solar filaments are best seen using an H-alpha filter, visible even with amateur telescopes, and resemble dark clouds which lie in the upper atmosphere of the Sun, the chromosphere and corona. Since many decades, solar physicists have tried to explain how filaments are formed, how they remain stable in the solar atmosphere and why they are sometimes violently expelled into space.
The image shows a possible scenario of a stable filament. The surface is represented by a continuum image and the filament (upper black structure) by an H-alpha image, both observed with the Dutch Open Telescope (La Palma, Spain). The magnetic field lines were inferred and interpreted using observations from the German Vacuum Tower Telescope (Tenerife, Spain). They are shown in different colors depending on their location on the Sun. In the image it is seen that the magnetic field lines support the filament's plasma against gravity. Furthermore, the field lines are responsible for the stability of the filament.
Image credit: Christoph Kuckein (AIP)
Publication: Kuckein et al., 2014, IAU Symposium 300, 40