Characteristics of the motion of coronal mass ejections and related shocks depending on the heliocentric distance

Abstract

The 3D characteristics of the coronal mass ejection (CME) body and shock at different distances (R) from the Sun’s center have been determined for several fast halo CMEs based on data from the Large Angle and Spectrometric Coronagraph Experiment (LASCO): the positions of the CME body boundary and the related shock on their axes, the directions and velocities of these points, the distance between a shock and the CME body boundary ΔR(R), and the difference between the velocities of these structures ΔV(R) and their angular dimensions. It was shown that the character of variations in the positions and velocities of the CME body boundary and a shock differs at different distances. The dependences of parameter [ΔR/Rcme](R), where Rcme is the curvature radius of the CME body boundary on the CME axis, were constructed. The obtained dependence was compared with the ΔR/Rcme (MA(R)) dependence. Here MA is the Alfven Mach number. The relation of ΔR/Rcme to MA was obtained by Russell and Mulligan (2002) for shocks in the Earth’s orbit. A comparison of [ΔR/Rcme](R) performed in two ways makes it possible to conclude that shocks related to a CME body are piston-like, with the CME body as a piston, at least at a distance of R > 10R0 (R0 is the solar radius).