Radioheliograph observations of metric Type II bursts and the kinematics of coronal mass ejections

Abstract

Assuming that metric type II radio bursts from the Sun are due to magnetohydrodynamic shocks driven by coronal mass ejections (CMEs), we estimate the average CME acceleration from its source region up to the position of the type II burst. The acceleration values are in the range ≈600-1240 \rm \;m\;s^{-2}, which are consistent with values obtained using non-radio methods. We also find that (1) CMEs with comparatively larger acceleration in the low corona are associated with soft X-ray flares of higher energy; the typical acceleration of a CME associated with X1.0 class soft X-ray flare being {\approx} 1020 \rm \;m\;s^{-2}, and (2) CMEs with comparatively higher speed in the low corona slow down quickly at large distances from the Sun—the deceleration of a CME with a typical speed of 1000 km s–1 being {\approx} {-}15 \rm \;m\;s^{-2} in the distance range of ≈3-32 R sun.