Detection of spike-like structures near the front of type-II bursts

Abstract

Aims. We examine high time resolution dynamic spectra for fine structures in type II solar radio bursts Methods. We used data obtained with the (SAO) receiver of the Artemis-JLS (ARTEMIS-IV) solar radio spectrograph in the 450-270 MHz range at 10 ms cadence and identified more than 600 short, narrowband features. Their characteristics, such as instantaneous relative bandwidth and total duration were measured and compared with those of spikes embedded in type IV emissions. Results. Type II associated spikes occur mostly in chains inside or close to the slowly drifting type II emission. These spikes coexist with herringbone and pulsating structures. Their average duration is 96 ms and their average relative bandwidth 1.7%. These properties are not different from those of type IV embedded spikes. It is therefore possible that they are signatures of small-scale reconnection along the type II shock front.

arXiv comment7 Pages 8 Figures, accepted for publication in Section 9. The Sun of Astronomy and Astrophysics

References in corpus (4)

• The improved ARTEMIS IV multichannel solar radio spectrograph of the University of Athens
• Millisecond microwave spikes: statistical study and application for plasma diagnostics
• High resolution observations with Artemis-IV and the NRH. I. Type IV associated narrow-band bursts
• Low frequency radio observations of bi-directional electron beams in the solar corona

Cited by in corpus (5)

• Solar Fast Drifting Radio Bursts in an X1.3 Flare on 2014 April 25
• Multi-wavelength Observations of a Metric Type-II Event
• First Frequency-Time-Resolved Imaging Spectroscopy Observations of Solar Radio Spikes
• High-resolution observations with ARTEMIS/JLS and the NRH: IV. Imaging spectroscopy of spike-like structures near the front of type-II bursts
• Observations of shock propagation through turbulent plasma in the solar corona