Prominences do the twist
posted: September 5, 2013

Two active prominences could be seen last week: one at the northeast limb close to the solar equator, the other at the northwest limb close to the Sun's northern pole. This movie shows the evolution of the two prominences from 26 till early 29 August. For both features, clips show their evolution at temperatures of around 50,000 (reddish) and 600,000 degrees (yellowish). They are followed by a movie combining the view through the previous 2 filters with that through SDO's AIA 094 filter (bluish; at a temperature of several million degrees). The movie ends with a view through SOHO's coronagraphs.

Both prominences are quite dynamical, but the northeast prominence shows a lot more activity and interaction with its surroundings. It also consists of more "cold" material than the polar prominence. This can be seen in the view through the AIA 171 filter: The northeast prominence consists mainly of dark patches (= much colder than 600,000 degrees; image above left) that follow the twisted magnetic field lines, whereas the polar prominence also contains a lot of "hot" material (not dark, emission; image above right).

The northeast prominence also seems to come to its ending in a more violent way, showing dynamical restructuring. However, no clear ejection of material away from the Sun can be seen. The flaring activity, visible as post flare loops and the bluish glow of hot material (AIA 094; images above), seems not to be related to this prominence activity and is very likely due to other activity coincidentally occurring in the same line-of-sight. Hence, the spectacular coronal mass ejection (CME) is probably a result of this flaring, and not due to the disappearance of the prominence.

The polar prominence seems to have a magnetic field structure that is less well defined. Hence, the material seems to move a bit less dynamically along the magnetic field lines. In the end, the mass of charged particles rises slowly, smoothly reconnecting and graciously leaving the solar surface. No flare-like phenomena were associated with the event, as is evident from the lack of bluish emission in the AIA 094 filter (images above). The accompanying CME is not very impressive (images below).

Credits - Imagery for the movie clips were taken from SDO and SOHO/LASCO.