Radio Triangulation of Type II Bursts Associated with a CME - CME Interaction

Abstract:

Coronal Mass Ejections (CMEs) are large-scale magnetized plasma disturbances propagating through the corona and the interplanetary (IP) medium. Along their path, some CMEs can drive shock waves, which accelerate ions and electrons. These fast electrons can generate type II radio bursts at the local plasma frequency and/or its first harmonic. In this study we use data from the two STEREO spacecraft which carry both imaging and radio instruments with direction-finding capabilities allowing us to track energetic electrons responsible for radio bursts. We present an analysis of type II bursts observed on the November 29 – 30, 2013. The shock wave signatures were possibly generated by an interaction of two consecutive CMEs. We have investigated three time-frequency intervals when received radio waves were sufficiently intense for direction-finding analysis. The obtained positions of triangulated radio sources suggest that the CMEs propagate towards the STEREO-A. The IP shock associated with this event has been also observed in situ by the MESSENGER and STEREO-A spacecraft.