Structured type III radio bursts observed in interplanetary space

Abstract

Context: The last few decades has seen numerous studies dedicated to fine structures of type III radio bursts observed in the metric to decametric wavelengths. Majority of explanations of the structured radio emission involve the propagation of electron beam through the strongly inhomogeneous plasma in the low corona. Until now only few studies of single type III bursts with fine structures, observed in the hecto-kilometric wavelengths, were reported. Aims: Herein we report about existence of numerous structured type III radio bursts observed during the STEREO era by all three WAVES instruments on board STEREO A, B, and Wind. The aim of the study is to report, classify structured type III bursts, and present the characteristics of their fine structures. The final goal is to try to understand the physical mechanism responsible for the generation of structured radio emission. Methods: In this study we used data from all available spacecraft, specifically the STEREO and the Wind spacecraft. We employ 1D density models to obtain the speed of the source of type III radio emission, the electron beam. We also perform spectral analysis of the fine structures in order to compare their characteristics with the metric-decametric fine structures. Results: The presented similarities of the type III fine structures in the metric to decametric and interplanetary wavelengths indicate that the physical processes responsible for the generation of structured type III radio bursts could be the same, at the heights, all the way from the low corona to the interplanetary range. We show that the observed structuring and intermittent nature of the type III bursts can be explained by the variation in the level of density fluctuations, at different distances from the Sun.

17 pages, 13 figures

References in corpus (12)

• A Review of Solar Type III Radio Bursts
• The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere
• Electrons in the Young Solar Wind: First Results from the Parker Solar Probe
• The formation heights of coronal shocks from 2D density and Alfvén speed maps
• Density Fluctuations in the Solar Wind Based on Type III Radio Bursts Observed by Parker Solar Probe
• Observational evidence for the associated formation of blobs and raining inflows in the solar Corona
• Statistics and Polarization of Type III Radio Bursts Observed in the Inner Heliosphere
• Using radio triangulation to understand the origin of two subsequent type II radio bursts
• Interferometric Imaging with LOFAR Remote Baselines of the Fine Structures of a Solar Type IIIb Radio Burst
• Harmonic radio emission in randomly inhomogeneous plasma
• Properties of Type III and Type IIIb Bursts in the Frequency Band of 8-80 MHz during PSP Perihelion at the Beginning of April 2019
• First observation of the solar Type III burst decay and its interpretation

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• The 17 April 2021 widespread solar energetic particle event
• Multiple injections of energetic electrons associated with the flare/CME event on 9 October 2021
• Observation of solar radio burst events from Mars orbit with the Shallow Radar instrument
• Electromagnetic radiation by turbulent, magnetized and randomly inhomogeneous solar radio sources generated by electron beams
• Coronal electron density: Insights from radio and in situ observations, and EUHFORIA modeling