Hot-Plasma Ejections Associated with Compact-Loop Solar Flares

TLDR

Masuda et al. observed hard X‑ray sources above soft X‑ray loops in impulsive compact‑loop flares, implying magnetic reconnection above the loop and predicting associated hot plasma ejections. The study aimed to detect hot plasma ejections in eight limb compact‑loop flares using Yohkoh soft‑X‑ray telescope images. Images from Yohkoh’s soft‑X‑ray telescope were analyzed for eight unbiasedly selected impulsive compact‑loop flares, including the Masuda 1992 January 13 event.

Abstract

Masuda et al. found a hard X-ray source well above a soft X-ray loop in impulsive compact-loop flares near the limb. This indicates that main energy release is going on above the soft X-ray loop, and suggests magnetic reconnection occurring above the loop, similar to the classical model for two ribbon flares. If the reconnection hypothesis is correct, a hot plasma (or plasmoid) ejection is expected to be associated with these flares. Using the images taken by the soft X-ray telescope aboard Yohkoh, we searched for such plasma ejections in eight impulsive compact-loop flares near the limb, which are selected in an unbiased manner and include also the Masuda flare, 1992 January 13 flare. We found that all these flares were associated with X-ray plasma ejections high above the soft X-ray loop and the velocity of ejections is within the range of 50-400 km s-1. This result gives further support for magnetic reconnection hypothesis of these impulsive compact-loop flares.