Solar radio bursts of spectral type II, coronal shocks, and optical coronal transients

The association of solar radio bursts of spectral type II and coronal shocks with solar flare ejecta observed in Hα, the green coronal line, and white-light coronagraphs is examined. Rather than identifying fast-moving optical coronal transients with outward-travelling shock waves that generate type II radio bursts, as has been suggested in some earlier papers, we suggest that, for the most part, such transients should probably be identified with piston-type phenomena well behind the shock. We then discuss a general model, consisting of three main velocity regimes, in which we relate type II radio bursts and coronal shocks to optically-observed ejecta. (orig.)