This is along a similar theme as last week's Nugget, in which we mentioned some of the changes that one can see in coronal loops during a solar flare. This week's Nugget focuses on a different flare, but the loop motions are no less spectacular.
The flare occurred on 27-Jan-99, at about 16:40 UT in the Sun's northern hemisphere. We will examine three sets of images, to see three different levels of motion.
The first movie is from the quarter-resolution images; this has the
widest field of view of our three movies. In this set of images (linked
below), we can see that the main structure of this fascinating flare consists
of two large bright bodies extending from east to west. Some motion in
these two bodies is apparent, but our eye is particularly drawn to the
flow observed in the loop to the west (to the right in these images).
For the second movie we zoom in a bit, to the half-resolution images. With these we are able to see the two main structures more clearly, and clearly observe all kinds of motion along their length. The two long structures exhibit a great deal of curvature, and there appears to be a thinner loop arching over them. Some faint expansion is visible in the south (towards the bottom), and the amount of curvature in the two main structures appears to change. Again, we can observe the flow along the loop in the west, just at the right-hand edge of the field of view.
Finally, we zoom in all the way to the full-resolution images. The evolution
of the loops in this movie raises a lot of questions. We can clearly see
the foreground loop leaning to the left (or are they new loops brightening,
one at a time, all in a row?), at the same time there appear to be field
lines connecting the foreground loop to those in the background, which
brighten during the movie. And what are the strange bright waves that ripple
through the foreground loop? Are they blobs of hot plasma travelling along
the magnetic field lines? Or are they local enhancements of the plasma
density caused by actual displacements of the magnetic field? Whatever
they are, they're moving at about 150-200 km/sec.