日冕物质抛射在低日冕中非均匀横向膨胀的光谱特征：基于ADITYA-L1/VELC的观测
Spectroscopic Signatures of Nonuniform Lateral Expansion of a Coronal Mass Ejection in the Low Corona with ADITYA-L1/VELC
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中文总结 AI 辅助
本研究利用ADITYA-L1/VELC光谱和AIA成像数据，分析2024年8月5日CME在低日冕的演化，结合三维几何-运动学模型，揭示了非均匀横向膨胀导致的双叉光谱形态，并约束了CME早期运动学分量。
中文摘要 AI 辅助
日冕物质抛射（CMEs）在低日冕（<2R☉）中经历快速演化，但其三维运动学仍缺乏有效约束。我们利用ADITYA-L1卫星上的可见发射线日冕仪（VELC）以及太阳动力学观测站（SDO）上的大气成像组件（AIA）对2024年8月5日观测到的一次日冕物质抛射进行了光谱和成像分析。VELC的Fe XIV 5303 Å光谱捕获了喷发中的CME穿过西部狭缝的过程。基于单高斯拟合的时空图揭示了喷发期间的日冕暗化以及增强的多普勒速度。详细的光谱分析揭示了与CME前沿相关的强多普勒位移的次级分量。这些分量在静止波长的两侧表现为两个空间分离的发射分支，在近乎静止且强度减弱的日冕发射之上产生了独特的双叉光谱形态。双高斯拟合得到的视线（LOS）等离子体速度高达218 km/s，这可能是下限，因为次级分量已到达光谱窗口边缘。AIA 211 Å观测测得的投影径向速度为1135 km/s，大于沿狭缝的平面天空（POS）横向速度692 km/s。为了解释观测到的CME演化及光谱结构，我们开发了一个简化的三维几何-运动学模型，用于描述膨胀的轴向倾斜CME壳层。该模型生成的合成光谱表明，经历不对称横向膨胀的倾斜CME可以产生与观测相似的双叉光谱形态，其速度分量分别投影在径向、POS横向和LOS横向方向上。我们的结果表明，将光谱学与极紫外（EUV）成像相结合，可以约束CME早期演化过程中的不同运动学分量。
英文摘要
Coronal mass ejections (CMEs) undergo rapid evolution in the low corona ($<2R_\odot$), yet their three-dimensional kinematics remain poorly constrained. We present a spectroscopic and imaging analysis of a CME observed on 2024 August 5 using the Visible Emission Line Coronagraph (VELC) on board ADITYA-L1 and Atmospheric Imaging Assembly (AIA)/Solar Dynamics Observator (SDO). The VELC Fe XIV 5303 Å spectra captured the erupting CME as it crossed the western slit. Space-time maps from single-Gaussian fits reveal coronal dimming and enhanced Doppler velocities during the eruption. Detailed spectral analysis reveals strongly Doppler-shifted secondary components associated with the CME front. These components appear as two spatially separated emission branches on opposite sides of the rest wavelength, producing a distinct bifurcated spectral morphology superposed on the nearly stationary reduced-intensity coronal emission. Double-Gaussian fitting yields line-of-sight (LOS) plasma velocities of up to 218 km/s, likely a lower limit as the secondary component reaches the edge of spectral window. AIA 211 Å observations measure a projected radial speed of 1135 km/s, larger than the plane-of-sky (POS) lateral speed of 692 km/s along the slit. To interpret the observed CME evolution and spectral structure, we developed a simplified three-dimensional geometric-kinematic model of an expanding axially tilted CME shell. Synthetic spectra from the model show that an inclined CME undergoing asymmetric lateral expansion can produce a bifurcated spectral morphology similar to that observed, with velocity components projected in the radial, POS-lateral, and LOS-lateral directions. Our results demonstrate that combining spectroscopy and EUV imaging constrains different components of CME kinematics during early evolution.
发表机构
- Indian Institute of Astrophysics（印度天体物理研究所）
- Pondicherry University（本地治里大学）
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