Electron acceleration and radio emission following the early interaction of two coronal mass ejections

Abstract

Context. Coronal mass ejections (CMEs) are large eruptions of magnetised plasma from the Sun that are often accompanied by solar radio bursts produced by accelerated electrons. Aims. A powerful source for accelerating electron beams are CME-driven shocks, however, there are other mechanisms capable of accelerating electrons during a CME eruption. So far, studies have relied on the traditional classification of solar radio bursts into five groups (Type I-V) based mainly on their shapes and characteristics in dynamic spectra. Here, we aim to determine the origin of moving radio bursts associated with a CME that do not fit into the present classification of the solar radio emission. Methods. By using radio imaging from the Nançay Radioheliograph, combined with observations from the Solar Dynamics Observatory, Solar and Heliospheric Observatory, and Solar Terrestrial Relations Observatory spacecraft, we investigate the moving radio bursts accompanying two subsequent CMEs on 22 May 2013. We use three-dimensional reconstructions of the two associated CME eruptions to show the possible origin of the observed radio emission. Results. We identified three moving radio bursts at unusually high altitudes in the corona that are located at the northern CME flank and move outwards synchronously with the CME. The radio bursts correspond to fine-structured emission in dynamic spectra with durations of ~1 s, and they may show forward or reverse frequency drifts. Since the CME expands closely following an earlier CME, a low coronal CME-CME interaction is likely responsible for the observed radio emission.

14 pages, 13 figures

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Cited by in corpus (8)

• Moving solar radio bursts and their association with coronal mass ejections
• Direct First PSP Observation of the Interaction of Two Successive Interplanetary Coronal Mass Ejections in November 2020
• Imaging-spectroscopy of a band-split type II solar radio burst with the Murchison Widefield Array
• Imaging and Spectral Observations of a Type-II Radio Burst Revealing the Section of the CME-Driven Shock that Accelerates Electrons
• Investigation of two coronal mass ejections from circular ribbon source region: Origin, Sun-Earth propagation and Geo-effectiveness
• Assessing the spectral characteristics of band splitting type II radio bursts observed by CALLISTO spectrometers
• Estimating the lateral speed of a fast shock driven by a coronal mass ejection at the location of solar radio emissions
• Estimating the total energy content in escaping accelerated solar electron beams