Two solar flares that became X-ray plasma ejections

TL;DR

This paper analyzes two exceptional solar events where flares and X-ray plasma ejections exhibited mixed features, revealing complex multi-stage evolution and different underlying physical processes, including magnetic flux emergence and reconnection.

Contribution

It presents detailed observations of two unique solar events with mixed flare and XPE features, highlighting their multi-stage evolution and distinct physical mechanisms.

Findings

Both events show four-stage evolution: rapid loop rise, emission changes, plasma release, final static loop.

Event 1's plasma ejection was halted by magnetic fields, while Event 2's ejection led to a CME.

The events involved different physical processes: flux emergence with reconnection versus reconnection with ballooning instability.

Abstract

Solar flares and X-ray plasma ejections (XPEs) occur simultaneously but usually are separated spatially. We present two exceptional events observed by {\sl Yohkoh} in 2001 October 2 (event 1) and 2000 October 16 (event 2), in which features of flares and XPEs are mixed. Namely, the soft and hard X-ray images show intense sources of emission that move dynamically. Both events occurred inside broad active regions showing complicated multi-level structure reaching up to 200 Mm high. Both events show also similar four-stages evolution: (1) a fast rise of a system of loops, (2) sudden changes in their emission distribution, (3) a reconfiguration leading to liberation of large amounts of plasma, (4) a small, static loop as the final remnant. Nevertheless, the events are probably caused by different physical processes: emerging magnetic flux plus reconnection (event 1) and reconnection plus ballooning instability (event 2). Different is also the final destination of the ejected plasma: in the event 1 overlying magnetic fields stop the ejection, in the event 2 the ejection destabilizes the overall magnetic structure and forms a coronal mass ejection (CME).