A complex filament eruption
posted: July 23, 2015

A movie of this event can be found here.

A very nice filament eruption occurred during the morning hours of 19 July. It was associated with a long-duration C2.1 flare that started at 09:22UT, peaked at 10:40UT, and ended at 13:02UT though it would take another 6 to 8 hours before the x-ray flux was back at its pre-event levels. The eruption of the filament itself took place between 07:00 and 10:00UT.

This eruption was very likely the result of an instability created by an earlier filament eruption in the northwest quadrant between 00:00 and 03:00UT. Indeed, in the first clip of this movie (SDO/AIA304; 00:00-12:00UT), one can see how this filament rises, but with a substantial part gliding back to the solar surface along the magnetic field lines very close to the up-to-then rather quiet filament near the southwest limb. After a brief eruption between 04:00 and 06:00UT, the filament then fully erupted starting around 07:00UT. The intricate details can be seen in a zoom of the region, i.e. in clip 2 (SDO/AIA304; 06:30-12:30UT), as well as in clip 3 combining AIA171 and AIA131 imagery showing a better contrast between the cold (dark purple) and hot (sky blue) areas of the eruption.

The images below are rotated stills from this combo clip showing the rise of the filament at 07:50UT, the eruption itself with some coronal dimming to the southeast ("bottom right") at 09:35UT, and finally the post-eruption coronal loops and the hot material on top of these series ("top left") at 11:55UT.

The associated coronal mass ejection (CME) was rather wide (about 120 degrees) and coincided with another, smaller CME to the northwest. It had a plane-of-the-sky speed of about 760 km/s and, though it was mostly directed away from the Earth, analysis of coronagraphic imagery revealed that this CME could deliver a glancing blow on 22-23 July.

Credits - Data and imagery for the movie clips were taken from SDO and (J)Helioviewer.