‘Fingerprint’ Fine Structure in the Solar Decametric Radio Spectrum Solar Physics

Abstract

We study a unique fine structure in the dynamic spectrum of the solar radio emis- sion discovered by the UTR-2 radio telescope (Kharkiv, Ukraine) in the frequency band of 20 - 30 MHz. The structure was observed against the background of a broadband type IV radio burst and consisted of parallel drifting narrow bands of enhanced emission and absorp- tion on the background emission. The observed structure differs from the widely known ze- bra pattern at meter and decimeter wavelengths by the opposite directions of the frequency drift within a single stripe at a given time. We show that the observed properties can be understood in the framework of the radiation mechanism by virtue of the double plasma res- onance effect in a nonuniform coronal magnetic trap. We propose a source model providing the observed frequency drift of the stripes.