Collision of emerging flux tubes at the photosphere as a result of the simultaneous emergence process (AR 11158). (a) Multiple-day tracking of magnetic polarities (color-coded traces on the heliographic plane) superimposed on a CEA magnetogram map of an intermediate time instance (at 2011 February 15 21:58 UT). The emergence occurred in two episodes per flux tube (marked as first and second episodes), with the second episode of emergence being stronger as compared to the first. Proper motions of polarities are more dramatic during the self-separation associated with the second episode per each bipole. As a result, a collision occurs between polarities N1 and P2. Overlaid squares mark the centroids of flaring activity (large square: M and X-class flares; small square: C-class flares). Note the containment of the activity along the collisional PIL. The dark-green squares denote events correlated with the emergence of the parasitic bipole north of N2 (see Figure 2) and are not included in our analysis (minor events in a different PIL; also marked in Table 1. (b) 3D spacetime representation of the collision using isosurfaces of ﹩| {\boldsymbol{B}}| =1,200﹩ G as viewed from the south. The squares show the location and time of activity, which is predominantly clustered at the collision site. An animation of panel (b) as a 3D flyby is available. The video duration is 7 s.

(An animation of this figure is available.)

The video/animation of this figure is available in the online journal.