Divergent
posted: April 2, 2015

Around noon on 27 March, a giant wall of solar plasma (charged particles) propelled itself into space. A movie of this event can be seen here.


Prominences are regions of dense and relatively cool material that are squeezed between fields of opposite magnetic polarity. They are seen at the solar limb, with typical values for height and length of resp. 30.000 km and 100.000 km. On the solar disk, they are seen as thin dark lines called filaments.


Last week's prominence clearly diverged from these typical values. In fact, just prior to its eruption, its height was at a steady 100.000 km, and with its length of at least 400.000 km it was even longer than the average earth-moon distance!


As this "wall of plasma" got ejected into space, the associated coronal mass ejection (CME) displayed its typical lightbulb shape: bright rim, dark cavity, and bright core filament. The CME was rather slow, with a plane-of-the-sky speed of only about 300 km/s. Though most of the prominence was ejected, some material can be seen falling back onto the solar surface, creating local brightenings.


The movie first shows a wide angle view of the event combining extreme ultraviolet (EUV) images from PROBA2 (1 million degrees) and SDO/AIA 304 (80.000 degrees). The clip covers nearly 3 days (25-27 March) and gives an idea of the extent of the wall as it appears from behind the northeast solar limb. The next clip covers 12 hours (06:00-18:00UT) and provides a zoom on the prominence and its evolution by combining SDO/AIA 304 (red) with AIA 193 (green; 1.3 million degrees) imagery. This zoom clearly shows the dynamics of the mass concentrations within the prominence. The final clip adds coronagraphic imagery from SOHO/LASCO C2.


Credits - Images for the movie clips were taken from SDO, SOHO/LASCO, PROBA2 and (J)Helioviewer.