发表机构
Aryabhatta Research Institute of Observational Sciences; Department of Applied Physics, Mahatma Jyotiba Phule Rohilkhand University; Department of Physics, Indian Institute of Technology Delhi; Department of Applied Physics/Physics, Bareilly College（阿里亚哈塔观测科学研究所; 马哈特马·乔蒂巴普勒罗希尔坎德大学应用物理系; 印度德里理工学院物理系; 巴雷利学院应用物理/物理系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出光流工具DOFCAT，结合ASPIICS和METIS数据，揭示CME前沿与核心的速度弥散及非均匀膨胀，发现高度差在2.3–3.0太阳半径快速增加，为CME内部动力学提供新见解。
AI 中文摘要
日冕物质抛射（CMEs）的内部速度分布尚未被充分理解。在本工作中，我们引入了一种基于光流的方法DOFCAT（稠密光流CME分析工具），并将其应用于ASPIICS/Proba-3和METIS/Solar Orbiter的高分辨率数据，以研究中日冕中CME内部不同子结构的内部速度弥散。我们还引入了一种高斯锥化傅里叶（GTF）滤波器，用于抑制ASPIICS宽带通道运行差分图像中的亮度伪影。随后，我们将DOFCAT应用于ASPIICS和METIS观测到的四个CME事件，提取其内部速度信息。我们的结果表明，CME前沿和核心的速度剖面均随位置角变化且非均匀。对于脉冲式CME，前沿与核心之间的高度偏移在脉冲加速阶段之后开始增加，而没有明显脉冲阶段的CME则表现出更渐进的高度偏移演化。我们发现，这种高度差的增加在2.3–3.0 R$_\odot$之间迅速发生。此外，前沿比核心表现出更高的速度弥散，脉冲性在CME前导半部中明显。我们进一步分别计算了前沿和核心的径向自相似系数，发现前沿最初以非自相似方式膨胀，并在较大高度处趋于自相似，而核心则保持相对自相似。这些发现证实，在传统的三部分形态中，CME包含复杂的内部流动和分层子结构。我们的结果证明了DOFCAT在高分辨率日冕仪上探测CME动力学的实用性，并为CME的触发和演化提供了新的见解。
英文摘要
Coronal mass ejections (CMEs) exhibit poorly understood internal velocity distributions. In this work, we introduce an optical flow-based method, DOFCAT (Dense Optical Flow CME Analysis Tool), applied to high-resolution data from ASPIICS/Proba-3 and METIS/Solar Orbiter to examine the internal velocity dispersion of different substructures within CMEs in the Middle Corona. We also introduce a Gaussian-tapered Fourier (GTF) filter that suppresses brightness artifacts in running-difference images from the ASPIICS wideband channel. We then apply DOFCAT to four CME events observed across ASPIICS and METIS, extracting their internal velocity information. Our results show that the velocity profiles of both the CME front and core change with position angle and are non-uniform. For impulsive CMEs, the height offset between the front and core begins to increase following the impulsive acceleration phase, while CMEs without a clear impulsive phase show a more gradual evolution of the height offset. We find that this increase in height difference occurs rapidly between 2.3--3.0\,R$_\odot$. Furthermore, the front shows a higher velocity spread than the core, with impulsiveness evident in the CME leading half. We further compute the radial self-similarity coefficient separately for the front and the core, finding that the front expands non-self-similarly initially and tends toward self-similarity at larger heights, while the core remains relatively self-similar. These findings confirm that CMEs contain complex internal flows and layered substructures within the traditional three-part morphology. Our results demonstrate the utility of DOFCAT on high-resolution coronagraphs for probing CME dynamics and provide new insights into CME initiation and evolution.
Comments22 pages; 10 figures. Accepted for publication in the Astrophysical Journal
