Coronal Mass Ejections, Flares and Type II Radio Bursts

An investigation of 210 interplanetary type II radio bursts and the associated white-light coronal mass ejections (CMEs) is presented. The radio bursts were detected by the Wind/WAVES experiment in the 1-14 MHz (decameter-hectometric, DH) range, while the CMEs were observed by the Solar and Heliospheric Observatory (SOHO). The study period, 1997-2002, encompasses the current solar cycle (23) between minimum and beyond maximum. We could only find 108 solar flares associated with DH type IIs. We obtained the difference onset times (solar flare - DH type II) and found that DH type IIs start at the same time as the flares. On the other hand the difference between CME and DH type II onset times is indicates that the type II bursts occur well after the CME onset. The present study suggests that the CMEs are more likely to be the source of the shocks responsible for the type II bursts. We extend the study to metric type II bursts and obtained similar results.