Eruption of EUV Hot-Channel near Solar Limb and Associated Moving Type-IV Radio Burst

TL;DR

This study analyzes a solar eruption involving a hot-channel flux rope near the limb, revealing its formation, eruption dynamics, and associated radio bursts, providing insights into the magnetic reconnection process and CME acceleration.

Contribution

It presents detailed observations of a hot-channel flux rope eruption, linking EUV features with radio bursts and flare ribbons, advancing understanding of eruption mechanisms.

Findings

Hot-channel flux rope formed via tether-cutting reconnection.

Eruption involved type-II, III, IVm radio bursts.

CME accelerated from slow rise to 8 m/s² during propagation.

Abstract

Using the observations from Solar Dynamics Observatory, we study an eruption of a hot-channel flux rope (FR) near the solar-limb on February 9, 2015. The pre-eruptive structure is visible mainly in EUV 131 $\mathring{\mathrm{A}}$ images with two highly-sheared loop structures. They undergo slow rise motion and then reconnect to form an eruptive hot-channel as in the tether-cutting reconnection model. The J-shaped flare-ribbons trace the footpoint of the FR which is identified as the hot-channel. Initially, the hot channel is observed to rise slowly at 40 km s$^{-1}$, followed by an exponential rise from 22:55 UT at a coronal height of 87$\pm$2 Mm. Following the onset of the eruption at 23:00 UT, the flare-reconnection adds to the acceleration process of the CME within 3 R$_\odot$. Later on, the CME continues to accelerate at 8 m s$^{-2}$ during its propagation period. Further, the eruption launched type-II followed by III, IVm radio bursts. The start and end times of type-IVm correspond to the CME core height of 1.5 and 6.1 R$_\odot$, respectively. Also the spectral index is negative suggesting the non-thermal electrons trapped in the closed loop structure. Accompanied with type-IVm, this event is unique in the sense that the flare ribbons are very clearly observed along with the erupting hot channel, which strongly supports that the hooked-part of J-shaped flare ribbons outlines the boundary of the erupting FR.