# Extreme-ultraviolet Late Phase Caused by Magnetic Reconnection over Quadrupolar Magnetic Configuration in a Solar Flare

## TL;DR

This study investigates the EUV late phase in solar flares, revealing that magnetic reconnection in a quadrupolar configuration causes additional heating and late-phase emissions, supported by observations and modeling.

## Contribution

It provides clear evidence linking late-phase EUV emissions to magnetic reconnection overlying the main flare loops in a quadrupolar magnetic setup, clarifying the heating source.

## Key findings

- Late-phase emission originates from longer or higher loops.
- Magnetic reconnection in overlying fields causes late-phase heating.
- EBTEL model successfully reproduces late-phase EUV emissions.

## Abstract

A second emission enhancement in warm coronal extreme-ultraviolet (EUV) lines (about 2-7 MK) during some solar flares is known as the EUV late phase. Imaging observations confirm that the late phase emission originates from a set of longer or higher loops than the main flare loops. Nevertheless, some questions remain controversial: What is the relationship between these two loop systems? What is the heating source of late phase emission, a heating accompany the main phase heating or occuring quite later? In this paper, we present clear evidence for heating source in a late-phase solar flare: magnetic reconnection of overlying field in a quadrupolar magnetic configuration. The event is triggered by an erupted core structure that eventually leads to a coronal mass ejection (CME). Cusp feature and its shrinkage motion high in the late-phase emission region are the manifestation of the later phase reconnection following the main flare reconnection. Using the enthalpy-based thermal evolution of loops (EBTEL) model, we reasonably reproduce the late-phase emissions in some EUV lines. We suggest that a continuous additional heating is responsible for the appearance of the elongated EUV late phase.