An investigation of flare emissions at multiple wavelengths

TL;DR

This study analyzes multi-wavelength observations of four solar flares, revealing differences in emission timing, temperature, and electron density, and highlighting the role of hot diffuse loops and erupting filaments.

Contribution

It provides detailed multi-wavelength analysis of solar flares, linking emission characteristics to flare dynamics and plasma properties, which is a novel comprehensive approach.

Findings

Three flares show delayed peak emissions in cooler EUV channels.

One flare exhibits simultaneous multi-wavelength emission and a type III radio burst.

Long-lasting flares have lower electron densities and are driven by hot diffuse loops.

Abstract

We report multi-wavelength observations of four solar flares on 2014 July 07. We firstly select these flares according to the soft X-ray (SXR) and extreme ultraviolet (EUV) emissions recorded by the Extreme Ultraviolet Variability Experiment and Geostationary Orbiting Environmental Satellites. Then their locations and geometries are identified from the full-disk images measured by the Atmospheric Imaging Assembly (AIA), and the time delays among the light curves in different channels are identified. The electron number densities are estimated using the Differential Emission Measure method. We find that three of four flares show strong emissions in SXR channels and high temperature (>6 MK) EUV wavelengths during the impulsive phase, i.e., AIA 131 A and 94 A, and then they emit peak radiation subsequently in the middle temperature (~0.6-3 MK) EUV channels. Moreover, they last for a long time and have smaller electron densities, which are probably driven by the interaction of hot diffuse flare loops. Only one flare emits radiation at almost the same time in all the observed wavelengths, lasts for a relatively short time, and has a larger electron density. It is also accompanied by a type III radio burst. The bright emission at the EUV channel could be corresponding to the associated erupting filament.