Evolution of eight CAs. Left column: different CAs represented by designated colors. Right column: same field lines but colored by the twist number. Rows, top to bottom: (a) initial normal coronal loop; (b) rotating flux rope accumulates twist; (c) unstable flux rope forms a writhe shape; (d) untwisting eruptive flux rope. An animation that covers the dynamic evolution of 72 minutes starting from t = t₀ is available. The real-time duration is 1.3 s.

(An animation of this figure is available in the online article.)

(An animation of this figure is available.)

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