Marvellous M-flares
posted: March 12, 2015

Though the Sun was devoid of big sunspot groups this week, no less than 9 M-class flares were recorded. These medium flares were produced by only 2 active regions: NOAA 2290 (5) and NOAA 2297. Interestingly, both regions were at the solar limb when they unleashed their flares. In fact, the last two (and strongest) M-class events of NOAA 2290 were produced when the region had already rounded the northwest solar limb, whereas NOAA 2297 had already released 2 of its 4 M-class events before it rounded the southeast limb.

Both regions were not very big, but they were magnetically complex. This resulted in two strong flares: NOAA 2290 produced an M8.2 flare on 03 March peaking at 01:35UT, and NOAA 2297 produced an M9.2 flare on 07 March peaking at 02:22UT. In all cases, the bulk of the related coronal mass ejections was not directed to Earth.

This movie shows 3 M-class flares in EUV as seen by SDO/AIA. It first shows the impressive eruption related to the M3.7 flare from NOAA 2290 on 02 March in temperatures of about 80.000 degrees (AIA304). This is followed by the duo of M-class flares early on 06 March (M3.0 and M1.5), showing a very hot cusp (pale blue flamelike feature) over the post-flare coronal loops. This clip combines images in hot temperatures (AIA131; blue; multimillion degrees) with images seen in the AIA171 filter (yellow; temperatures around 700.000 degrees). The last clip shows the impressive coronal loops that followed the M9.2 flare late on 07 March (AIA171).