Plasma evolution within an erupting coronal cavity

TL;DR

This study provides spectroscopic observations of an erupting coronal cavity, revealing rapid flux rope expansion, plasma flows, and the relationship between flare energy release and cavity dynamics.

Contribution

First spectroscopic analysis of an erupting coronal cavity, linking flare energy flux to flux rope eruption and plasma flow dynamics.

Findings

Rapid cavity eruption associated with increased flare energy flux

Observation of plasma flows from the flux rope apex that cease after eruption

Disappearance of filamentary material as the cavity forms

Abstract

Coronal cavities have previously been observed associated with long-lived quiescent filaments and are thought to correspond to the associated magnetic flux rope. Although the standard flare model predicts a coronal cavity corresponding to the erupting flux rope, these have only been observed using broadband imaging data, restricting analysis to the plane-of-sky. We present a unique set of spectroscopic observations of an active region filament seen erupting at the solar limb in the extreme ultraviolet (EUV). The cavity erupted and expanded rapidly, with the change in rise phase contemporaneous with an increase in non-thermal electron energy flux of the associated flare. Hot and cool filamentary material was observed to rise with the erupting flux rope, disappearing suddenly as the cavity appeared. Although strongly blue-shifted plasma continued to be observed flowing from the apex of the erupting flux rope, this outflow soon ceased. These results indicate that the sudden injection of energy from the flare beneath forced the rapid eruption and expansion of the flux rope, driving strong plasma flows which resulted in the eruption of an under-dense filamentary flux rope.