[论文解读] Infrared spectropolarimetry of a C-class solar flare footpoint plasma -- I. Spectral features and forward modelling

Z. Vashalomidze, C. Quintero Noda+11 more|arXiv (Cornell University)|Feb 24, 2026

Solar and Space Plasma Dynamics被引用 0

一句话总结

论文展示两次连续C类太阳耀斑的高时空分辨红外光谱偏振测量，分析多条光球层和色球层的线，使用带有多分量色球层板的前向建模来解读He I 10830 Å轮廓的复杂性。

ABSTRACT

We performed high-spatial resolution spectropolarimetric observations of active region NOAA 13363 during a C-class flare with the Gregor Infrared Spectrograph (GRIS) on 16 July 2023. We examine the coupling between the photosphere and the chromosphere, studying the polarimetric signals during a period that encompasses the decaying phase of a C-class flare and the appearance of a new C-class flare at the same location. We focus on the analysis of various spectral lines. In particular, we study the Si I 10827 Å, Ca I 10833.4 Å, Na I 10834.9 Å, and Ca I 10838.9 Å photospheric lines, as well as the He I 10830 Å triplet. GRIS data revealed the presence of flare-related red- and blueshifted spectral line components, reaching Doppler velocities up to 90 km/s, and complex Si I profiles where the He i spectral line contribution is blueshifted. In contrast, the photospheric Ca i and Na i transitions remained unchanged, indicating that the flare did not modify the physical conditions of the lower photosphere. We combined that information with simultaneous imaging in the Ca ii H line and TiO band with the improved High-resolution Fast Imager (HiFI+), finding that the flare emission did not affect the inverse granulation or nearby plage, in agreement with the results from GRIS. We also complement the previous studies with a forward modelling computation, concluding that the He I spectral line emission reflects a complex response of the flaring chromosphere. Radiative excitation from coronal EUV irradiation, energy deposition by flare-accelerated electrons, and dynamic field-aligned plasma flows likely act together to produce the observed supersonic downflows and upflows. We plan to expand these findings through inversions of the He I 10830 Å triplet signals in the future.

研究动机与目标

• 了解耀斑活动如何改变足点区域的光球层与色球层光谱线。
• 表征Si I 10827 Å、Ca I 10833 Å、Na I 10834 Å和He I 10830 Å在衰减与 impulsive 燃烧阶段的多普勒位移与线轮廓变化。
• 探讨在HAZEL框架内的多分量色球层板的前向建模如何再现观测到的He I 10830 Å轮廓。
• 评估耀斑期间能量沉积与等离子体流动的意义。

提出的方法

• 围绕10830 Å的高时空分辨Stokes光谱偏振测量，使用Gregor红外光谱仪（GRIS）。
• 对Si I 10827 Å、Ca I 10833 Å、Na I 10834 Å、Ca I 10838 Å和He I 10830 Å三重峰的Stokes I与V进行分析。
• 在HAZEL框架内使用多分量色球层进行前向建模，以再现复杂的He I轮廓。
• 多步法：合成具有不同数量的色球层分量和LOS速度的轮廓，以匹配观测形状。
• 使用Ca II H和TiO HiFI+成像以及SDO/HMI-AIA数据进行情景成像与磁场背景分析。
• 讨论将宽广He I轮廓与非热运动及通过β增强因子在HAZEL中的等效过占据联系起来的可能性。

Figure 1: Temporal evolution of the Fried-parameter $r_{0}$ (black bullets) and air mass (solid line) during the 2023 July16 observations with the 1.5-metre Gregor solar telescope. The light grey rectangle corresponds to the time interval of the HiFI+ observations. The black bullets were taken from

实验结果

研究问题

• RQ1 耀斑相关活动在He I 10830 Å三重峰及附近光球层线中有哪些光谱特征和多普勒位移？
• RQ2 多分量色球层模型如何在衰减与 impulsive 燃烧阶段再现观测到的复杂He I 10830 Å轮廓？
• RQ3 观测到的线轮廓变化对耀斑足点的能量沉积、等离子体流动和磁场结构有何启示？

主要发现

• 观察到与耀斑相关的红移与蓝移分量，Doppler速度高达约90 km s^-1，He I 10830 Å发射指示色球层响应的复杂性。
• 光球层Ca I与Na I线大体保持不变，表明在耀斑期间下层光球层修改有限。
• He I 10830 Å轮廓宽广，常需要多个色球层分量（有的发射、有的吸收）来再现观测形状。
• 基于FALC光球层加多分量色球层的前向建模可以再现非常宽的He I轮廓，意味着高多普勒宽度（15–25 km s^-1）和显著非热运动。
• 宽广的He I分量暗示He I三重峰上态的过人口增多，可能通过耀斑驱动的过电离与辐射泵浦，在HAZEL中通过增强因子β进行建模。
• 研究发现一个一致的模式：He I发射与强烈色球层加热和动态流动相关，而光球层线的响应有限。

Figure 2: Collection of SDO observations taken at around 08:48 UT. Co-aligned Gregor/GRIS slit-scan and HiFI+ FOVs are shown as red and green (TiO) as well as white (Ca ii H) rectangles, respectively. The locations of the first flare (FL1) and second flare (FL2) are labelled in each panel. Bottom le