Title: The nature of small scale EUV solar brightenings investigated as impulsive heating of short loops in 1D hydrododynamics simulations Show Chinese title

Title: 小尺度EUV太阳增亮现象的性质被研究为一维流体力学模拟中短环的脉冲加热

Abstract: Small (400 to 4000 km) and short lived (10 to 200 km) extreme ultraviolet (EUV) brightenings, detected by the High Resolution Imager EUV (HRIEUV), have been found to be ubiquitous in the Quiet Sun (QS). Their contribution to coronal heating as well as their physical origin are currently being investigated. We wish to determine whether models of short loops and impulsive heating are compatible with the results from observations. In particular, we used two models of loops with distinct thermal properties: cool (T below 1E5 K) and hot loops (T above 1E5 K). We simulated the evolution of impulsively heated short loops, using the 1D hydrodynamics (HD) code HYDRAD. We computed the synthetic light curves of HRIEUV, four EUV channels of the Atmospheric Imaging Assembly (AIA), and five emission lines measured by the SPectral Imaging of the Coronal Environment (SPICE). We then compared the results from the synthetic light curves with observations. The aim was to reproduce the short delays observed between the intensity peaks of the light curves. Cool loops subjected to impulsive heating are good candidates to explain the physical origin of the EUV brightenings. On the other hand, hot loops are not consistent with observations, except when they are subjected to especially strong impulsive heating. Show Chinese abstract

Abstract: 小型（400至4000公里）且短寿命（10至200公里）的极端紫外线（EUV）增亮现象，由高分辨率成像极紫外仪（HRIEUV）探测到，在宁静太阳（QS）中普遍存在。目前正研究它们对日冕加热的贡献及其物理起源。我们希望确定短环和脉冲加热模型是否与观测结果一致。特别是，我们使用了具有不同热特性的两种环模型：冷环（温度低于1E5 K）和热环（温度高于1E5 K）。我们用一维流体力学代码HYDRAD模拟了脉冲加热的短环演化。我们计算了HRIEUV的合成光变曲线、大气成像组件（AIA）的四个EUV通道以及由日冕环境光谱成像仪（SPICE）测量的五个发射线的光变曲线。然后我们将合成光变曲线的结果与观测结果进行了比较。目标是重现光变曲线强度峰值之间的短延迟。受脉冲加热影响的冷环是解释EUV增亮现象物理起源的良好候选者。另一方面，除非受到特别强烈的脉冲加热，否则热环与观测结果不一致。