Source location and evolution of a multi-lane type II radio burst

Abstract

Shocks in the solar corona can accelerate electrons that in turn generate radio emission known as type II radio bursts. The characteristics and morphology of these radio bursts in the dynamic spectrum reflect the evolution of the shock itself, together with the properties of the local corona where it propagates. In this work, we study the evolution of a complex type II radio burst showing a multi-lane structure, to find the locations where the radio emission is produced and relate them to the properties of the local environment. Using radio imaging, we track separately each lane composing the type II burst and relate the position of the emission to the properties of the ambient medium such as density, Alfven speed, and magnetic field. We show that the radio burst morphology in the dynamic spectrum changes with time and it is related to the complexity of the local environment. The initial stage of the radio emission show a single lane in the spectrum, while the latter stages of the radio signature evolve in a multi-lane scenario. The radio imaging reveals how the initial stage of the radio emission separates with time into different locations along the shock front as the density and orientation of the magnetic field change along the shock propagation. At the time where the spectrum shows a multi-lane shape, we found a clear separation of the imaged radio sources. By combining radio imaging with the properties of the local corona, we described the evolution of a type II radio burst and, for the first time, identified three distinct radio emission regions above the CME front. Two regions were located at the flanks, producing earlier radio emission than the central position, in accordance with the complexity of density and Alfven speed values in the regions where radio emission is generated. This unprecedented observation provides new insights into the nature of multi-lane type II bursts.

References in corpus (20)

• LOFAR: The LOw-Frequency ARray
• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• Imaging Spectroscopy of Solar Radio Burst Fine Structures
• The formation heights of coronal shocks from 2D density and Alfvén speed maps
• Multiple Regions of Shock-accelerated Particles during a Solar Coronal Mass Ejection
• Shock location and CME 3D reconstruction of a solar type II radio burst with LOFAR
• Emission of Type II Radio Bursts - Single-Beam versus Two-Beam Scenario
• Heating of the partially ionized solar chromosphere by waves in magnetic structures
• A broken solar type II radio burst induced by a coronal shock propagating across the streamer boundary
• The Coronal Veil
• Type II radio bursts and their association with coronal mass ejections in solar cycles 23 and 24
• Evolution of the Alfvén Mach number associated with a coronal mass ejection shock
• LOFAR observations of a jet-driven piston shock in the low solar corona
• Imaging of the Quiet Sun in the Frequency Range of 20-80 MHz
• Imaging-spectroscopy of a band-split type II solar radio burst with the Murchison Widefield Array
• Solar coronal density turbulence and magnetic field strength at the source regions of two successive metric type II radio bursts
• RFI Flagging in Solar and Space Weather Low Frequency Radio Observations
• Resolving spatial and temporal shock structures using LOFAR observations of type II radio bursts
• Determining the acceleration regions of in situ electrons using remote radio and X-ray observations
• Imaging and spectropolarimetric observations of a band-split type II solar radio burst with LOFAR