Interplanetary Radio Emission: A Summary of Recent Results

TL;DR

This paper reviews recent findings in low-frequency solar radio physics, focusing on radio bursts, their connection to solar eruptions, and new phenomena like diffuse interplanetary radio emission, using data from multiple spacecraft.

Contribution

It introduces new observations of diffuse interplanetary radio emission and discusses the directivity of interplanetary type IV bursts, advancing understanding of solar radio phenomena.

Findings

Diffuse interplanetary radio emission (DIRE) linked to CME-driven shocks

Directivity characteristics of interplanetary type IV bursts analyzed

Evolution of a solar noise storm over two rotations observed

Abstract

This paper summarizes some recent results in the low-frequency radio physics of the Sun. The spatial domain covers the space from the outer corona to the orbit of Earth. The results obtained make use of radio dynamic spectra and white-light coronagraph images and involve radio bursts associated with solar eruptions and those occurring outside solar eruptions. In particular, the connection between type II radio bursts and the sustained gamma-ray emission from the Sun is highlighted. The directivity of interplanetary type IV bursts found recently is discussed to understand the physical reason behind it. A new event showing the diffuse interplanetary radio emission (DIRE) is introduced and its properties are compared with those of regular type II bursts. The DIRE is from the flanks of a CME-driven shock propagating through nearby streamer. Finally, a new noise storm observed by two spacecraft is briefly discussed to highlight its evolution over two solar rotations including the disruption and recovery by solar eruptions.