Type II radio bursts and energetic solar eruptions

Abstract

We report on a study of type II radio bursts from the Wind/WAVES experiment in conjunction with white‐light coronal mass ejections (CME) from the Solar and Heliospheric Observatory (SOHO). The type II bursts considered here have emission components in all the spectral domains: metric, decameter‐hectometric (DH) and kilometric (km), so we refer to them as m‐to‐km type II bursts. CMEs associated with the m‐to‐km type II bursts were more energetic than those associated with bursts in any single wavelength regime. CMEs associated with type II bursts confined to the metric domain were more energetic (wider and faster) than the general population of CMEs but less energetic than CMEs associated with DH type II bursts. Thus the CME kinetic energy seems to organize the life time of the type II bursts. Contrary to previous results, the starting frequency of metric type II bursts with interplanetary counterparts seems to be no different from that of type II bursts without interplanetary counterparts. We also verified this by showing that the average CME height at the onset time of the type II bursts is the same for the two metric populations. The majority (78%) of the m‐to‐km type II bursts were associated with solar energetic particle (SEP) events. The solar sources of the small fraction of m‐to‐km type II bursts without SEP association were poorly connected to the observer near Earth. Finally, we found that the m‐to‐km type II bursts were associated with bigger flares compared to the purely metric type II bursts.