Subjects: Astronomy submitted time 2023-12-15 Cooperative journals: 《天文学报》
Abstract： The corona is a key region of solar atmospheric activity, and the source of solar-terrestrial space weather. Limited by observation, research on the plasma structure and magnetic field state of the lower coronal atmosphere is still very lacking, and there are few international studies on the brightness stratification of the lower coronal atmosphere in the visible light band.In this paper, the coronal green line ($ rm Fe_{ Rmnum{14}}$5303 ; AA) observation data of Lijiang coronagraph YOGIS (Yunnan Green-line Imaging System) is used to analyze the bright structure and mid-coronal loops in the inner coronal region (1.03$R_{ odot}$--1.25$R_{ odot}$) effectively. By fitting the exponential decay of the intensity of the bright structures at the radial height of the sun, comparing these fitting results, it is found that the decay index of the static inner coronal loops obtained is around a fixed value. Then, the more obvious coronal loops are extracted, and by performing the same exponential fitting on the intensities of different heights, the obtained decay index is also relatively similar to that of the bright structure, which provides a reference for further study of the evolution of physical parameters in the corona.
Subjects: Astronomy >> Astrophysics submitted time 2023-05-16
Abstract： The corona is a key region of solar atmospheric activity,and the source of solar-terrestrial space weather.Limited by observation,research on the plasma structure and magnetic field state of the lower coronal atmosphere is still very lacking, and there are few international studies on the brightness stratification of the lower coronal atmosphere in the visible light band.In this paper,the coronal green line (FeXIV 5303 Å)
observation data of Lijiang coronagraph YOGIS is used to analyze the bright structure and mid-coronal loops in the inner coronal region (1.03R⊙-1.25R⊙) effectively.By fitting the exponential decay of the intensity of the bright structures at the radial height of the sun,comparing these fitting results,it is found that the decay index of the static inner coronal loops obtained is around a fixed value.Then,the more obvious coronal loops are extracted,and by performing the same exponential fitting on the intensities of different heights,the obtained decay index is also relatively similar to that of the bright structure,which provides a reference for further study of the evolution of physical parameters in the corona.
Subjects: Astronomy >> Astrophysical processes submitted time 2021-11-12 Cooperative journals: 《天文研究与技术》
Abstract：本文利用SDO(Solar Dynamic Observatory)/HMI(Helioseismic and Magnetic Imager)观测到的矢量磁图，运用Ampere定律的积分形式计算出了2014年11月7日活动区AR12205上发生X1.6级耀斑期间的垂直电流密度，通过分析光球层上垂直电流密度的时间演化，发现它会在耀斑爆发期间表现出突然的增加，增加的区域对应于耀斑双带的辐射增强位置，然后将强电流密度轮廓叠加在SDO/AIA1600 Å波段的观测图像上，发现电流密度的形态与分布和耀斑带有强相互关系。这些观测结果与三维标准耀斑模型的理论预测一致，我们的研究为三维磁准分界面（Quasi-Separatrix Layer，QSL）重联模型提供了有力的观测证据。
Subjects: Astronomy >> Astrophysical processes submitted time 2020-11-19 Cooperative journals: 《天文研究与技术》
Abstract：太阳高能活动爆发与活动区内的电流结构有着密切的联系，安培（Ampere）定律j_z=〖1/μ_0 (∇×B)〗_z是测量活动区内视向电流密度的理论基础。由于实测的矢量磁场中不可避免地存在随机噪声，因此，应用安培定律的不同形式计算的电流密度存在显著的差异。为了比较不同形式计算结果的差异并从中探索一种实用的电流计算方法，基于太阳动力学天文台(Solar Dynamic Observatory,SDO)/HMI(Helioseismic and Magnetic Imager)在2011年2月15日测量的活动区AR11158的矢量磁图，运用安培定律的微分算法和积分算法分别计算了活动区内视向电流密度的分布图。结果显示，微分算法获得的视向电流密度j_z分布图受随机噪声的影响要远比积分算法获得的结果大，电流分布图中的电流结构没有积分算法获得的结果清晰。另外，在扩大积分环路半径的情况下，所计算的电流分布图里的噪声信号快速降低，从而使计算的视向电流分布图中的电流结构更清晰。但是当继续扩大积分环路半径时，在获得清晰电流分布图的同时，电流分布图的部分精细结构也随之失真。该研究结果论证了适当扩大积分环路计算视向电流分布图可以降低计算结果受随机噪声的影响，从而获得清晰真实的视向电流分布图，但是积分路径的半径过大在消除噪声影响的同时会丢失电流分布中的一些精细结构。因此在实际计算电流的过程中，应该利用高分辨率的矢量磁图，选定合适的积分路径运用安培定律的积分算法来计算活动区的视向电流，从而帮助我们探索耀斑爆发与活动区内电流结构的关系。
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