One of last week's highlights certainly was the M1.6-flare in NOAA 1692 near the northwest limb of the Sun. Starting late on 21 March at 21:42UT, it reached its peak flux at 22:04UT and ended at 22:36UT. The event was not accompanied by an energetic proton enhancement.
The flare took place in a quite simple sunspot group. Interestingly, this group had already produced an M1-flare on 15 March which caused a moderate geomagnetic storm 2 days later (see last week's STCE Newletter). As the group neared the west limb, it developed some opposite polarity flux in front of the main spot, but the potential interaction was difficult to evaluate. See SDO white light image, magnetogram and AIA171 picture taken around the time of the flare maximum (underneath).
This movie contains several clips mixing different color components of the various wavelengths as observed by the SDO/AIA instrument. This allows for views of the eruption in different temperature ranges. The first clip combines AIA 171, 193 and 304 imagery, the second clip blends AIA 171, 193 and 131, and the last clip mixes AIA 171, 094 and 304. Preliminary analysis suggests that the blue, cusp like structure contains hot (multimillion degrees) plasma from the outflow of the reconnection event. This conclusion requires further verification, as the various wavelengths contain temperature bands that (partially) overlap.
From these marvelous images, one can conclude that this was a quite energetic event and, judging from the dynamic changes in the post-flare coronal loops, also a very complex one.
The movie ends with 2 clips from the accompanying coronal mass ejection (CME). The bright dot to the lower right is the planet Venus, which is actually at the other side of the Sun and at a distance of over 250 million kilometers from the Earth. The zoom-in clip reveals the complex structure of this CME, which was not headed for Earth.
Credits - Images were taken from SDO, SOHO and PROBA2, and processed with Helioviewer and JHelioviewer.
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