Imaging Observations of Chromospheric Evaporation in a Circular-ribbon Flare
Imaging Observations of Chromospheric Evaporation in a Circular-ribbon Flare
复制标题
圆带状耀斑中色球层蒸发的成像观测
DOI：
10.3847/1538-4357/aaf4b7
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发表时间：
2019
影响因子：
4.9
通讯作者：
Huang Y
中科院分区：
文献类型：
--
作者：
Zhang Q M;Li D;Huang Y
本文报道了2014年8月24日C5.5级圆带状耀斑（CRF）色球蒸发的多波长成像观测结果。太阳动力学观测站上的大气成像组件（AIA）、日出号航天器上的X射线望远镜（XRT）和地面的野边山射电日像仪观测到了耀斑。CRF由一个直径为1.5 μ m的离散的圆形带和一个短的内带组成，在紫外（UV）、极紫外、软X射线（SXR），特别是在17 GHz下观察到。耀斑在17 GHz的峰值时间（0.04：58 UT）与UV1600 GHz和SXR导数的硬X射线替代值相吻合，表明低层大气中的脉冲能量沉积峰值时间。在峰值时间之后不久，AIA 131射电望远镜和两个XRT滤光片（Be_thin和Be_med）显示了耀斑环中的会聚运动和填充过程，这是色球蒸发上升流的明显证据。色球层蒸发持续了106分钟，直到105：04 UT。上升流的温度、密度和视速度分别为107 K、101.8 × 1010 cm−3和50−630 km s−1，平均值为170 km s−1。通过与以前的模型比较，我们能够估计，可能需要5 × 1010 erg cm−2 s−1以上的能量才能解释观测结果。由于热传导加热似乎不能提供足够的能量，因此可能需要调用非热电子或阿尔夫文波等替代机制。
In this paper, we report our multiwavelength imaging observations of chromospheric evaporation in a C5.5 circular-ribbon flare (CRF) on 2014 August 24. The flare was observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, the X-ray Telescope (XRT) on board the Hinode spacecraft, and the ground-based Nobeyama Radioheliograph. The CRF consisted of a discrete circular ribbon with a diameter of ∼1′ and a short inner ribbon observed in ultraviolet (UV), extreme-ultraviolet, soft X-ray (SXR), and especially in 17 GHz. The peak time (∼04:58 UT) of the flare in 17 GHz coincided with that in UV 1600 Å and SXR derivative as a hard X-ray proxy, implying the peak time of impulsive energy deposition in the lower atmosphere. Shortly after the peak time, converging motion and filling processes in the flare loop were revealed in AIA 131 Å and two XRT filters (Be_thin and Be_med), which are clear evidence for chromospheric evaporation upflows. The chromospheric evaporation lasted for ∼6 minutes until ∼05:04 UT. The temperature, density, and apparent velocities of the upflows are ∼107 K, ∼1.8 × 1010 cm−3, and 50−630 km s−1 with a mean value of ∼170 km s−1. By comparison with previous models, we are able to estimate that energies above 5 × 1010 erg cm−2 s−1 are likely needed to explain the observational results. Since heating by thermal conduction does not seem to provide enough energy, alternative mechanisms such as nonthermal electrons or Alfvénic waves might need to be invoked.