SDO/AIA Detection of Solar Prominence Formation within a Coronal Cavity

TL;DR

This study analyzes SDO/AIA observations to understand the formation of a solar prominence within a coronal cavity, highlighting plasma cooling, transport, and in situ condensation processes that support magneto-thermal convection models.

Contribution

First detailed analysis of prominence formation within a coronal cavity using multi-wavelength SDO/AIA data, revealing plasma cooling and condensation mechanisms.

Findings

Prominence formation involves plasma cooling and condensation.

Bright emission cloud appears before prominence formation.

Cavity darkening correlates with prominence growth.

Abstract

We report the first analyses of SDO/AIA observations of the formation of a quiescent polar crown prominence in a coronal cavity. The He II 304 \AA\ (log T_{max} ~ 4.8 K) data show both the gradual disappearance of the prominence due to vertical drainage and lateral transport of plasma followed by the formation of a new prominence some 12 hours later. The formation of the prominence is preceded by the appearance of a bright emission "cloud" in the central region of the coronal cavity. The peak brightness of the cloud progressively shifts in time from the Fe XIV 211 \AA\ channel, through the Fe XII 193 \AA\ channel, to the Fe IX 171 \AA\ channel (log T_{max} ~ 6.2, 6.1, 5.8 K, respectively) while simultaneously decreasing in altitude. Filter ratio analysis estimates the initial temperature of the cloud in the cavity to be approximately log T \sim 6.25 K with evidence of cooling over time. The subsequent growth of the prominence is accompanied by darkening of the cavity in the 211 \AA\ channel. The observations imply the possibility of prominence formation via in situ condensation of hot plasma from the coronal cavity, in support of the proposed process of magneto-thermal convection in coronal magnetic flux ropes.