KMS of Xinjiang Astronomical Observatory, CAS
| 太阳射电爆发纤维结构的观测统计研究 | |
| Alternative Title | Observational Statistical Research on the Fiber Fine Structure of Solar Radio Bursts |
万俊麟
| |
| Subtype | 硕士 |
| Thesis Advisor | 唐建飞 |
| 2021-12-01 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Name | 理学硕士 |
| Degree Discipline | 天体物理 |
| Keyword | 太阳物理,太阳耀斑,射电爆发,纤维精细结构 |
| Abstract | 太阳上发生剧烈爆发时，在射电波段的辐射会出现迅速增强的现象，我们称之为太阳射电爆发。太阳的射电爆发根据波段分类, 可分为米波、分米波和微波爆发等多种，其中微波爆发与太阳耀斑爆发密切相关，二者来源于同一太阳大气区域。太阳耀斑会加速并发射出大量高能带电粒子，这些高能粒子将会对空间卫星和地面电网乃至宇航员的安全产生威胁。然而可见光、近红外和紫外波段的观测设备是很难观测到像高能粒子的加速和传播这样的高能过程。这些高能过程在射电望远镜的观测下，将显著表现为各类射电爆发现象，太阳射电爆发和其中的精细结构各自对应着不同太阳物理过程中非热粒子的加速和传播过程。纤维结构是太阳射电爆发中一种常见且重要的精细结构，于 1961 年由 Young 首次发现。在太阳射电动态频谱图中，纤维结构往往同时具有发射和吸收结构，常成群出现并呈负向漂移，一般存在于太阳射电 IV 型暴中。太阳射电 II 型爆和 III型爆源于不同的物理过程，而纤维结构的频漂率介于太阳射电 II 型暴和 III 型暴之间，这一特性使得学者们对纤维结构究竟由什么物理机制产生而感到困惑。目前，对于纤维结构的研究主要集中于米波和分米波波段，对于微波波段的纤维爆发研究甚少, 尤其是统计研究工作。1975 年，Kuijpers 首先提出了纤维结构的理论解释，即哨声波理论，后又提出了阿尔文孤子模型等来解释纤维结构的产生。但纤维结构的各类理论解释模型都没能完美的解释纤维爆发的产生和特征，对纤维结构的统计研究工作也许能使理论解释得到进一步发展。 论文第一章简短介绍了太阳射电爆发分类和频谱精细结构的观测特性，并总结了太阳射电辐射机制。1.4 节中介绍了几类重要的频谱精细结构的基本特征。论文第二章介绍了纤维结构的主要观测特性，并讨论了纤维结构的主流理论模型。论文第三章着重介绍了作者的统计研究。基于国家天文台怀柔观测站的太阳射电宽带动态频谱仪 2000 - 2006 年在三个频段上的射电数据，作者共观测到 48个耀斑中 82 个清晰的纤维爆发事件。结合软 X 射线、硬 X 射线和日本野边山的高频微波数据对耀斑和纤维爆发事件进行了多波段分析。3.1 和 3.2 节主要介绍了相关观测设备和数据处理方法。82 个纤维爆发事件中，作者测量了 937 根清晰完整纤维结构的持续时间、带宽、频漂率和偏振度等参数。3.4 节为主要统计结果，负向漂移的 915 根纤维结构的平均持续时间、相对带宽和相对频漂率大约为1.22 s、6.31 %和-0.069 \s，左旋圆偏振（LCP）和右旋圆偏振（RCP）纤维结构的偏振度平均值分别为 62.3 % 和 67.1 %。根据不同耀斑等级和相位，我们对纤维结构的参数做了分类统计研究。不同于以往的文献结果，作者发现超过 40% 的纤维爆发事件，发生于耀斑前相和上升相。大多数纤维爆发事件在时间上与 HXR 或微波爆发有关，这表明纤维爆发与非热高能电子密切相关。并且，纤维结构的持续时间与相对频漂率呈双曲线关系。在 3.5 节作者运用哨声波模型和阿尔文孤子模型分别计算了磁场强度等物理参数，其中由哨声波模型得到的结果与斑马纹的观测结果更为一致。论文第四章为本论文主要研究结果的总结及今后研究工作的展望。 |
| Other Abstract | During violent eruptions on the Sun, there is a rapid increase in emission at radio wavelengths, called solar radio bursts. Solar radio bursts can be classified into meter wave, decimeter wave and microwave burst according to the band classification. Microwave burst is closely related to solar flare bursts, and they come from the same solar atmosphere region. Solar flares accelerate and shoot out large amounts of energetic particles, which can threaten space satellites, ground power grids and even astronauts. However, it is difficult to observe energetic processes such as the acceleration and propagation of energetic particles with observation equipment in the visible, near infrared and ultraviolet wavelengths. However, these energetic processes, observed by radio telescopes, will be manifested in various kinds of radio bursts. These solar radio bursts and their fine structures correspond to the acceleration and propagation of non-thermal particles in different solar physical processes. Fiber structures, first discovered by Young in 1961, are common and important fine structures in solar radio bursts. In the solar radio dynamic spectrum, the fiber structures often have both emission and absorption structures, and often appear in groups with negative drift. They generally exist in solar radio type IV bursts. Solar radio type II burst and type III burst are caused by different physical processes, and the frequency drift rate of the fiber structure is between that of solar radio type II burst and type III burst, which makes scholars confused about the physical mechanism of the fiber structure. At present, the research on fiber structure mainly focuses on the meter wave and decimeter wave band, and the research on fiber burst in microwave band is very little, especially the statistical research work. In 1975, Kuijpers first proposed a theoretical explanation of fiber structure, namely whistle wave theory, and then Alfvén soliton model is proposed. However, all kinds of theoretical explanation models of fiber structure can not perfectly explain the generation and characteristics of fiber burst, and statistical research on fiber structure may enable further development of theoretical explanation. The first chapter briefly introduces the classification of solar radio bursts and the observation characteristics of the fine structure of the spectrum, and summarizes the mechanism of solar radio bursts. The basic characteristics of several important types of spectral fine structures are described in Section 1.4. In chapter 2, the main observed characteristics of fiber structure are introduced and the main theoretical models of fiber structure are discussed. The third chapter focuses on the author’s statistical research. Based on the radio data of the Solar Radio Wideband Dynamic Spectrum Instrument from 2000 to 2006 in three frequency bands, we observed 82 clear fiber bursts in 48 flares. A multi-band analysis of flares and fiber burst events was performed combining soft X-ray, hard X-ray and high frequency microwave data from Nobian Mountain, Japan. Sections 3.1 and 3.2 mainly introduce relevant observation equipment and data processing methods. We measured the duration, bandwidth, frequency drift rate and degree of polarization of 937 clear and intact fibers from 82 fiber burst events. Section 3.4 shows the main statistical results. The average duration, relative bandwidth and relative frequency drift rate of 915 fiber structures with negative drift are about 1.22s, 6.31% and -0.069 /s. The average degree of polarization of left and right circularly polarized fibers is 62.3 % and 67.1 %, respectively. The fiber structure parameters of different flare grades and phases were statistically compared. Contrary to previous literature, we found that more than 40% of the fiber burst events occurred in the preflare and ascending phases. Moreover, most of the fiber burst events are related to HXR or microwave burst in time, suggesting that fiber burst is closely related to non-thermal high-energy electrons. The relationship between the duration of fiber structure and relative frequency drift rate is hyperbolic. In Section 3.5, the author calculated the magnetic field and other physical parameters by using the whistle wave model and Alfvén soliton model respectively, and the results obtained by the whistle wave model were more consistent with the zebra pattern observation results. The fourth chapter is the summary of the main research results and the prospect of future research. |
| Pages | 68 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xao.ac.cn/handle/45760611-7/5159 |
| Collection | 研究生学位论文 |
| Affiliation | 中国科学院新疆天文台 |
| First Author Affilication | Xinjiang Astronomical Observatory, Chinese Academy of Sciences |
| Recommended Citation GB/T 7714 | 万俊麟. 太阳射电爆发纤维结构的观测统计研究[D]. 北京. 中国科学院大学,2021. |
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