X‐Ray and Radio Studies of a Coronal Eruption: Shock Wave, Plasmoid, and Coronal Mass Ejection

TLDR

A fast 900 km s⁻¹ X‑ray eruptive structure and a slower 180 km s⁻¹ plasmoid were observed on 1994 July 31, associated with a coronal mass ejection, prominence eruption, and multiple metric radio bursts, including type II, IV, and III signatures. The study shows that the X‑ray eruption drives the coronal shock wave, producing type II and herringbone bursts when it crosses open magnetic fields, and that mass addition to type III burst sources raises plasma levels, thereby clarifying the CME’s X‑ray manifestation and answering the long‑standing question of shock‑wave origins.

Abstract

On 1994 July 31, a fast (900 km s-1) eruptive structure was observed in X-rays, followed by a slower plasmoid (180 km s-1). They were associated with a coronal mass ejection, prominence eruption, and a host of metric radio bursts. The X-ray structure seems to be a part of a white light coronal mass ejections (CME), as inferred from the white light images of July 30 and 31. A type II burst was observed at the leading edge of the X-ray eruption, while a type IV burst was spatially associated with the detached plasmoid. The type III radio bursts occurred on thin overdense structures associated with the eruption. We detected the rise of plasma levels because of mass addition to the type III burst sources as a result of the eruption. This event further clarifies the manifestation of a CME in X-rays. We identify the X-ray eruption as the driver of the coronal shock wave. This provides answer to the long-standing question regarding the origin of coronal and interplanetary shock waves. We have also found evidence to support the idea that herringbone bursts are produced when the coronal shock wave crosses open magnetic field lines.