Multi-Viewpoint Observations of X-Class Flares and Associate CMEs 2010-2014

Abstract:

The coronagraph systems carried on STEREO A &B as well as SOHO were used to collect data above the limb of the visible disk over the period 2011-2014. This corresponds roughly to the maximum of solar cycle24. EUV telescopes on the two STEREO spacecraft as well as those located on the SDO platform provided disk imagery of the EUV chromosphere and corona. About one third of the events examined occurred on the backside of the sun as viewed from Earth and have little or no signature detected with the GOES X-ray Flux instruments.

The spatial resolution used ranges from 3-arc sec in the EUV Disk observations to 30-arc sec in the corona at 20 solar radii. Time sequences with a cadence of 5-10 minutes were used for disk and coronagraph collection rates.

Of particular interest are the association of major flare activity and the detection of large halo-type mass ejection events. In a majority of cases (34 of 37 events, a four part sequence of events was detected by the combined instrument systems.

These include (1) flare initiation and early onset (2)Large-Scale Coronal Propagating Fronts(LCPF), The properties of these features were measured using the collection of EUV He II 304 and Fe XII 193 disk imagers. (3) Evacuation of material from the lower corona 1-4solar radii was visualized appearing behind a bright front CME arch in coronagraph images of the lower corona (STEREO and SOHO) and (4) formulation of a CCME structure where mass expands 3-dimensionally into the corona as visualized from 4 to 20 solar radii as the CME leaves the Sun (C2 SOHO and Cor2 STEREO). In the cases of large X- class flares, a small reduction of the brightness (1-6 %of pre-flare) in F XIII 193 image sequences. These reduced emission features are seen easily in the running difference data for periods of scores of minutes following flare initiation. These transient features are centered on the originating active region and are highly correlated in space and time with the coronagraph observations. Disk structure of reduced intensity is dynamic and has final scale size of a fraction of a solar diameter. This suggests a method of detecting major CME initiation from disk active regions that does not require use of coronagraphic technique.