Long, Stable Filament

As the STEREO (Ahead) observed, a very long filament remained stable over a two-day period (Feb. 6-7, 2012) as viewed in extreme UV light. The filament, the darker U-shaped strand, curves down from left of the top down to mid latitude, then back up to the right. Other than becoming more evident to the viewer, it does not change a lot. The cooler material in the filament doesn't emit radiation at this wavelength, unlike its hotter surroundings in the corona. Sustained by magnetic forces, filaments can last for weeks, but are often unstable and erupt. We'll keep an eye on this one. Note: The darker "T" shaped structure to the left of the filament is a coronal hole.

• 195_filament_big.mov   
• 195_filament_small.mov   
• 195_filament_big.mpg   
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