Solar type III bursts with high‐frequency cut‐off

Abstract

BackgroundSolar activity often manifests in type III bursts. Some of them can have high‐frequency cut‐off. The origin of this phenomenon is unclear until now.Materials and MethodsNew results in the study of solar bursts with high‐frequency cut‐off observed with the UTR‐2 radio telescope are presented. The bursts were associated with the emergency of a new group of solar spots behind the solar limb relative to an observer on the Earth.ResultsWe have identified the radio events with type III by analyzing its frequency drift rate, duration and flux depending on frequency. The cut‐off feature is considered in the context of specific effects of radio wave propagation between the burst sources moving behind the solar limb and the ground‐based radio instruments.ConclusionsThe role of tunnel‐like cavities with low density in the solar corona can be crucial for the emergence of solar decameter bursts with high‐frequency cut‐off.