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

## TL;DR

This study analyzes high-resolution solar radio spectra to identify spike-like structures near type-II bursts, revealing their properties and suggesting they may indicate small-scale reconnection events at the shock front.

## Contribution

It provides the first detailed characterization of spike-like structures near type-II bursts and compares them with those in type IV emissions, proposing a possible physical origin.

## Key findings

- Spikes occur mainly in chains near type II emissions.
- Average spike duration is 96 ms with 1.7% bandwidth.
- Properties are similar to spikes in type IV emissions.

## 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.