Understanding CME and associated shock in the solar corona by merging multi wavelengths observation

TL;DR

This study combines multi-wavelength observations to analyze a complex eruptive solar event involving a jet and CME, revealing their interaction and associated radio bursts without relying on density models.

Contribution

It provides a detailed analysis of the CME and shock development using combined EUV, white light, and radio data, including the first joint spectral and imaging observations of a type II burst.

Findings

CME initiated by magnetic reconnection with the eruptive jet.

Two successive type II radio bursts linked to CME evolution.

First direct measurement of B-field and Alfvén speed from radio data.

Abstract

Using multi-wavelength imaging observations, in EUV, white light and radio, and radio spectral data over a large frequency range, we analyzed the triggering and development of a complex eruptive event. This one includes two components, an eruptive jet and a CME which interact during more than 30 min, and can be considered as physically linked. This was an unusual event. The jet is generated above a typical complex magnetic configuration which has been investigated in many former studies related to the build-up of eruptive jets; this configuration includes fan-field lines originating from a corona null point above a parasitic polarity, which is embedded in one polarity region of large Active Region (AR). The initiation and development of the CME, observed first in EUV, does not show usual signatures. In this case, the eruptive jet is the main actor of this event. The CME appears first as a simple loop system which becomes destabilized by magnetic reconnection between the outer part of the jet and the ambient medium. The progression of the CME is closely associated with the occurrence of two successive types II bursts from distinct origin. An important part of this study is the first radio type II burst for which the joint spectral and imaging observations allowed: i) to follow, step by step, the evolution of the spectrum and of the trajectory of the radio burst, in relationship with the CME evolution; ii) to obtain, without introducing an electronic density model, the B-field and the Alfven speed.