Dynamics of CMEs in the LASCO Field of View

Abstract

A large set (16 000) of coronal mass ejections (CMEs) observed during 1996 – 2011 was selected to study their dynamics in the LASCO field of view (LFOV). These events were selected based on the criterion that at least three height–time measurements were available for each CME. The height–time measurements included in the SOHO/LASCO catalog were used to determine velocities and accelerations of the respective CMEs at successive distances from the Sun. Next, these parameters were sorted into 30 subsamples depending on the distance from the Sun at which they were determined. The mean velocities and accelerations calculated for the successive distance-dependent subsamples of CMEs were used to study their dynamics. We demonstrate that CMEs in the LFOV manifest three distinct phases of propagation: (i) The propelling Lorentz force dominates the dynamics of CMEs in the inner (C2 LASCO) FOV, (ii) a stable propagation occurs as a result of the balance between the propelling and drag forces, (iii) the drag force dominates at the outer edge of the LFOV. When we considered different categories of CME separately, we found different acceleration–distance profiles for different categories.