Twisting beauties
posted: May 20, 2015

Some very nice prominence and filament eruptions were observed over the last week. In this MOVIE, four major events are shown in the combined filters of SDO's AIA 304 ("cool"; about 80.000 degrees; red) and AIA 193 ("hot"; about 1.3 million degrees; green). Prominences and filaments usually lay dormant until the surrounding magnetic fields become unstable and eject the material into space. As the plasma traces the untwisting magnetic field lines, it often shows an helical ("corkscrew") motion. More info on these features can be found in e.g. the newsitems at 2 April 2015, 5 March 2015, and 5 November 2014.

The first eruption took place early on 09 May near the northeast solar limb and was associated with a C7.4 flare peaking at 01:34UT. It was also preceded by a filament eruption in the northeast quadrant, which may have triggered the limb event. The movie clip covers both eruptions and runs from 08 May at 23:30UT till 09 May at 03:30UT. Earth was not affected by the associated coronal mass ejection (CME).

The second eruption took place on 12 May at the west limb and was associated to a C2.6 flare peaking at 03:02UT. The clip covers the event from 01:30UT till 04:30UT. The event enhanced the greater than 10 MeV proton flux (energetic particles), but the flux remained below the alert threshold.

On 13 May, a filament erupted in NOAA 2345, close and to the east ("left") of big active region NOAA 2339. It was associated with the strongest flare of last week, a C9.2 flare peaking at 18:18UT. The bulk of the CME was directed to the north, but a faint full halo CME could be distinguished in difference images made by SOHO's LASCO/C2 coronagraph. Moving very slowly, it either passed the Earth unnoticed or got mixed with the arrival on 18 May of the high speed stream of a nearby recurrent coronal hole.

In the night of 15-16 May, a long and dynamic filament impressively erupted near the northeast limb. A few hours later it was followed by the eruption of a nearby, much smaller filament to the west. No obvious flares were associated with these events, and the CMEs had no earth-directed component.