An Eruptive Hot-Channel Structure Observed at Metric Wavelength as a Moving Type-IV Solar Radio Burst

TL;DR

This study presents the first radio imaging of a hot channel structure in the solar corona at metric wavelengths, revealing its association with a moving type-IV burst and providing insights into the structure's dynamics and emission mechanisms.

Contribution

It is the first to image an eruptive hot channel in the metric wavelength range and analyze its associated moving type-IV radio burst, offering new constraints on emission mechanisms.

Findings

Radio sources co-move with the hot channel, indicating electron trapping.

Sources show little dispersion early, then spread along the structure later.

High brightness temperature and evolving spectral shape characterize the burst.

Abstract

Hot channel (HC) structure, observed in the high-temperature passbands of the AIA/SDO, is regarded as one candidate of coronal flux rope which is an essential element of solar eruptions. Here we present the first radio imaging study of an HC structure in the metric wavelength. The associated radio emission manifests as a moving type-IV (t-IVm) burst. We show that the radio sources co-move outwards with the HC, indicating that the t-IV emitting energetic electrons are efficiently trapped within the structure. The t-IV sources at different frequencies present no considerable spatial dispersion during the early stage of the event, while the sources spread gradually along the eruptive HC structure at later stage with significant spatial dispersion. The t-IV bursts are characterized by a relatively-high brightness temperature ($\sim$ 10$^{7}$ $-$ 10$^{9}$ K), a moderate polarization, and a spectral shape that evolves considerably with time. This study demonstrates the possibility of imaging the eruptive HC structure at the metric wavelength and provides strong constraints on the t-IV emision mechanism, which, if understood, can be used to diagnose the essential parameters of the eruptive structure.