engleski

The role of reconnection in the initiation, acceleration, and interplanetary propagation of CMEs

The central issue of the presentation is the role of reconnection in the acceleration of coronal mass ejections (CMEs). Following basic physical concepts it is demonstrated that impulsive acceleration of fast CMEs is not possible without reconnection. In the absence of reconnection the magnetic flux associated with the erupting structure remains conserved, causing the inductive decay of the electric current and cessation of the Lorentz force. Under such circumstances, the acceleration is constrained to values in the order of 100 m s‑ 2 and acts over distances too short to provide velocities ˜ 1000 km s‑ 1 . However, if the flare-associated reconnection in the wake of the erupting flux-rope supplies the rope with additional poloidal flux, the Lorentz-force acceleration can attain values up to 10 km s‑ 2 and prolong to large heights. The results of a simple analytical model of a semitoroidal line-tied flux-rope are confronted with observations: various aspects of the CME-flare relationship are addressed, particularly emphasizing proxy measurements of the reconnected flux. Beside this central topic, the role of reconnection in the evolution and destabilization of the pre-eruptive structure is discussed, focusing on scenarios that lead to loss of equilibrium. Finally, the effect of reconnection ahead/aside of the CME during its propagation through the upper corona and interplanetary space is addressed.

Coronal mass ejections

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