Extreme Ultraviolet Late Phase of Solar Flares

Abstract

A second peak in extreme ultraviolet sometimes appears during the gradual phase of solar flares, which is known as EUV late phase (ELP). Stereotypically ELP is associated with two separated sets of flaring loops with distinct sizes, and it has been debated whether ELP is caused by additional heating or extended plasma cooling in the longer loop system. Here we carry out a survey of 55 M-and-above GOES-class flares with ELP during 2010--2014. Based on the flare-ribbon morphology, these flares are categorized as circular-ribbon (19 events), two-ribbon (23 events), and complex-ribbon (13 events) flares. Among them, 22 events (40%) are associated with coronal mass ejections, while the rest are confined. An extreme ELP, with the late-phase peak exceeding the main-phase peak, is found in 48% of two-ribbon flares, 37% of circular-ribbon flares, and 31% of complex-ribbon flares, suggesting that additional heating is more likely present during ELP in two-ribbon than in circular-ribbon flares. Overall, cooling may be the dominant factor causing the delay of the ELP peak relative to the main-phase peak, because the loop system responsible for the ELP emission is generally larger than, and well separated from, that responsible for the main-phase emission. All but one of the circular-ribbon flares can be well explained by a composite "dome-plate" quasi-separatrix layer (QSL). Only half of these show a magnetic null point, with its fan and spine embedded in the dome and plate, respectively. The dome-plate QSL, therefore, is a general and robust structure characterizing circular-ribbon flares.

arXiv commentaccepted for publication in AAS journals

References in corpus (22)

• An Observational Overview of Solar Flares
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: SHARPs -- Space-weather HMI Active Region Patches
• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
• Preprocessing of vector magnetograph data for a non-linear force-free magnetic field reconstruction
• Structure, Stability, and Evolution of Magnetic Flux Ropes from the Perspective of Magnetic Twist
• Generalized Squashing Factors for Covariant Description of Magnetic Connectivity in the Solar Corona
• Hot Spine Loops and the Nature of a Late-Phase Solar Flare
• Circular Ribbon Flares and Homologous Jets
• A trilinear method for finding null points in a 3D vector space
• Enthalpy-based Thermal Evolution of Loops: II. Improvements to the Model
• X-ray and UV investigation into the magnetic connectivity of a solar flare
• An Unorthodox X-Class Long-Duration Confined Flare
• Flux rope, hyperbolic flux tube, and late EUV phases in a non-eruptive circular-ribbon flare
• On the origin of the Extreme-Ultraviolet late phase of solar flares
• Production of the Extreme-Ultraviolet Late Phase of an X Class Flare in a Three-Stage Magnetic Reconnection Process
• Investigating Energetic X-Shaped Flares on the Outskirts of A Solar Active Region
• On the Nature of the Extreme-Ultraviolet Late Phase of Solar Flares
• Thermodynamic Spectrum of Solar Flares Based on SDO/EVE Observations: Techniques and Statistical Results
• Extremely Large Extreme-ultraviolet Late Phase Powered by Intense Early Heating in a Non-eruptive Solar Flare
• Probing the Production of Extreme-ultraviolet Late-Phase Solar Flares by Using the Model Enthalpy-Based Thermal Evolution of Loops
• Extreme-ultraviolet Late Phase Caused by Magnetic Reconnection over Quadrupolar Magnetic Configuration in a Solar Flare
• Extremely Large EUV Late Phase of Solar Flares

Cited by in corpus (11)

• Ultra-high-resolution Observations of Persistent Null-point Reconnection in the Solar Corona
• A Seven-Day Multi-Wavelength Flare Campaign on AU Mic I: High-Time Resolution Light Curves and the Thermal Empirical Neupert Effect
• FastQSL: A Fast Computation Method for Quasi-separatrix Layers
• Hinode/EIS coronal magnetic field measurements at the onset of a C2 flare
• Partial Eruption, Confinement, and Twist Buildup and Release of a Double-decker Filament
• Investigation on the Spatiotemporal Structures of Supra-Arcade Spikes
• The Influence of Different Phases of a Solar Flare on Changes in the Total Electron Content in the Earth's Ionosphere
• Sigmoid Formation Through Slippage of A Single J-shaped Coronal Loop
• Implications for additional plasma heating driving the extreme-ultraviolet late phase of a solar flare with microwave imaging spectroscopy
• Energy partition in a confined flare with an extreme-ultraviolet late phase
• Extreme-ultraviolet Late Phase in Homologous Solar Flares from a Complex Active Region