Monday, 25 November 2013

Enigmatic Returnee

The big spot appearing around the Sun's eastern limb may, sometimes, be a 'relic' of an earlier group. 'Helio' freeware (c) Peter Meadows left no doubt that giant AR11899 was the return of the 'front end' or preceding (p) spot of October's giant AR11875: it had moved a little westwards while on the Sun's far-side. New (red) spots arose near it on Nov 13 and a C3 flare erupted along the filament (arf) to its north. The 'smiley face' (lhs) shows most of what remained of the AR11875 (p) spot in late Oct. This very large earlier group had two X-class flares during it disc passage, one at the western limb (see below). Renamed AR11899, it grew to 600 area units in size during Nov with fields in the big spot's umbra reaching a SC24 record of 2700G.

Friday, 15 November 2013

X2.3 in AR11875

Five logs showing a GOES X2.3 flare in AR11875 (Nov 29 UT)- we see the flare arcade above the limb: the spot group is now behind the limb. Over the next 30min the flare arcade evolves into post flare loops while surges erupt nearby. Big surge s1 is retracting in log5 - causing a splash, it seems, in the chromosphere.

Monday, 4 November 2013

C5.7 flare in AR11875

This small but bright flare was seen while much stronger GOES M-class and even X-class were erupting. The polarities of spots have been added (c) Mt Wilson. They show a complex mingling of unlike polaries and red polarities 'ahead' of the great preceding spot - little wonder that strong flares were active in this complex group. It would host an X2.3 when at the Sun's western limb a week later.