The Relation Between Large-Scale Coronal Propagating Fronts and Type II Radio Bursts

Abstract

Large-scale, wave-like disturbances in extreme-ultraviolet (EUV) and type II radio bursts are often associated with coronal mass ejections (CMEs). Both phenomena may signify shock waves driven by CMEs. Taking EUV full-disk images at an unprecedented cadence, the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory has observed the so-called EIT waves or large-scale coronal propagating fronts (LCPFs) from their early evolution, which coincides with the period when most metric type II bursts occur. This article discusses the relation of LCPFs as captured by AIA with metric type II bursts. We show examples of type II bursts without a clear LCPF and fast LCPFs without a type II burst. Part of the disconnect between the two phenomena may be due to the difficulty in identifying them objectively. Furthermore, it is possible that the individual LCPFs and type II bursts may reflect different physical processes and external factors. In particular, the type II bursts that start at low frequencies and high altitudes tend to accompany an extended arc- shaped feature, which probably represents the 3D structure of the CME and the shock wave around it, rather than its near-surface track, which has usually been identified with EIT waves. This feature expands and propagates toward and beyond the limb. These events may be characterized by stretching of field lines in the radial direction, and be distinct from other LCPFs, which may be explained in terms of sudden lateral expansion of the coronal volume. Neither LCPFs nor type II bursts by themselves serve as necessary conditions for coronal shock waves, but these phenomena may provide useful information on the early evolution of the shock waves in 3D when both are clearly identified in eruptive events.

21 pages, 9 figures, accepted for publication in Solar Physics. Here, it became 24 pages long, but the original PDF file is available at bit.ly/1m0401J

References in corpus (8)

• Advances in Observing Various Coronal EUV Waves in the SDO Era and Their Seismological Applications (Invited Review)
• Quasi-periodic Fast-mode Wave Trains Within a Global EUV Wave and Sequential Transverse Oscillations Detected by SDO/AIA
• The Kinematics of a Globally Propagating Disturbance in the Solar Corona
• Anomalous Expansion of Coronal Mass Ejections during Solar Cycle 24 and its Space Weather Implications
• Off-limb Solar Coronal Wavefronts From SDO/AIA EUV Observations - Implications For Particle Production
• Quasiperiodic acceleration of electrons by a plasmoid-driven shock in the solar atmosphere
• Soft X-ray Fluxes of Major Flares Far Behind the Limb as Estimated Using STEREO EUV Images
• CorPITA: An Automated Algorithm for the Identification and Analysis of Coronal "EIT Waves"

Cited by in corpus (7)

• A Statistical Analysis of the Solar Phenomena Associated with Global EUV Waves
• Multi-wavelength Observations of a Metric Type-II Event
• Projection effects in coronal dimmings and associated EUV wave event
• Contribution of Velocity Vortices and Fast Shock Reflection and Refraction to the Formation of EUV Waves in Solar Eruptions
• Cross-loop propagation of a quasi-periodic extreme-ultraviolet wave train triggered by successive stretching of magnetic field structures during a solar eruption
• Spectral Structures of Type II Solar Radio Bursts and Solar Energetic Particles
• Earth-affecting Solar Transients: A Review of Progresses in Solar Cycle 24