Production of the Extreme-Ultraviolet Late Phase of an X Class Flare in a Three-Stage Magnetic Reconnection Process

TL;DR

This paper analyzes an X class solar flare's three-stage magnetic reconnection process, linking EUV late phase emissions with distinct magnetic activities and proposing a comprehensive model for flare evolution.

Contribution

It introduces a novel three-stage magnetic reconnection scenario explaining the EUV late phase in solar flares, supported by multi-instrument observations.

Findings

EUV late phase corresponds to the third stage of flare evolution.

Distinct magnetic reconnections produce the late phase loops.

Continuous energy injection leads to warm corona in late phase loops.

Abstract

We report observations of an X class flare on 2011 September 6 by the instruments onboard the Solar Dynamics Observatory (SDO). The flare occurs in a complex active region with multiple polarities. The Extreme-Ultraviolet (EUV) Variability Experiment (EVE) observations in the warm coronal emission reveal three enhancements, of which the third one corresponds to an EUV late phase. The three enhancements have a one-to-one correspondence to the three stages in flare evolution identified by the spatially-resolved Atmospheric Imaging Assembly (AIA) observations, which are characterized by a flux rope eruption, a moderate filament ejection, and the appearance of EUV late phase loops, respectively. The EUV late phase loops are spatially and morphologically distinct from the main flare loops. Multi-channel analysis suggests the presence of a continuous but fragmented energy injection during the EUV late phase resulting in the warm corona nature of the late phase loops. Based on these observational facts, We propose a three-stage magnetic reconnection scenario to explain the flare evolution. Reconnections in different stages involve different magnetic fields but show a casual relationship between them. The EUV late phase loops are mainly produced by the least energetic magnetic reconnection in the last stage.