Could the collision of CMEs in the heliosphere be super-elastic? Validation through three-dimensional simulations

Though coronal mass ejections (CMEs) are magnetized fully ionized gases, a recent observational study of a CME collision event in 2008 November has suggested that their behavior in the heliosphere is like elastic balls, and their collision is probably superelastic [C. Shen et al., 2012]. If this is true, this finding has an obvious impact on the space weather forecasting because the direction and velocity of CMEs may change. To verify it, we numerically study the event through three-dimensional MHD simulations. The nature of CMEs' collision is examined by comparing two cases. In one case, the two CMEs collide as observed, but in the other, they do not. Results show that the collision leads to extra kinetic energy gain by 3-4% of the initial kinetic energy of the two CMEs. It firmly proves that the collision of CMEs could be superelastic. Key Points Collision of CMEs in the heliosphere could be super-elastic Magnetic energy is the major source of kinetic energy gain Extra gain of kinetic energy may influence space weather.