The location and propagation of fine structures in type II solar radio bursts

Solar eruptions such as coronal mass ejections can drive collisionless shocks that are good particle accelerators. Electrons accelerated by these shocks can be observed remotely via the electromagnetic emission they generate at low radio frequencies. The radio signatures of shock-accelerated electrons at the Sun are type II radio bursts that can be used to track the propagation of the shock wave in the solar corona and beyond. However, type II radio bursts can have complex morphologies in dynamic spectra, being composed of numerous fine time and frequency structures. Here, we aim to determine the location and propagation of the fine structures composing type II bursts using radio imaging from the Nançay Radioheliograph. We investigate the origin of a type II radio burst that was only co-temporal with a flare and a coronal wave, and it was not associated with a CME eruption. The type II burst still showed complex morphology. We find that emission lanes and fine structures composing the type II burst originate from multiple locations around the flare site. The source regions also move in peculiar non-uniform propagation directions following the shock expansion. Our findings are consistent with the idea that multiple radio emission source regions form as a shock propagates through the solar corona.