| 太阳小尺度结构的观测特征及物理机制的研究 |
| 其他题名 | The Studies on Observational Characteristics and Physical Mechanism of Solar Small-scale Structures
|
| 邓林华
|
| 学位类型 | 博士
|
| 导师 | 屈中权
|
| 2014-05-26
|
| 学位授予单位 | 中国科学院研究生院（云南天文台）
|
| 学位授予地点 | 北京
|
| 学位专业 | 天体物理
|
| 关键词 | 太阳磁场
太阳活动
光球亮点
极区光斑
统计技术
|
| 摘要 | 太阳磁场结构在太阳表面大气层上表现为各种不同的空间尺度,目前国内外最先进的太阳观测设备的衍射极限正在接近理论预言的最小磁场结构(磁元)的尺度范围。观测数据和数值模拟都揭示出太阳表面大气层上的小尺度磁结构是无处不在的但并非是绝对的均匀分布,这些小尺度磁结构提供了太阳辐射绝大部分的能量来源。虽然它们不像剧烈耀斑爆发和日冕物质抛射具有极其壮观的景象,但是不能忽视它们在太阳物理中的重要地位,因为它们对于认识和揭示太阳全球／局部湍流发电机理论、色球和日冕加热机制、太阳风的起源和加速、磁流浮现与对消等还未完全理解的领域具有相当重要的科学意义。 近半个世纪以来,对太阳小尺度磁结构的研究是太阳物理领域中一项被普遍关注且高度重视的前沿课题之一。尽管太阳小尺度磁结构的观测特征及其物理机制的研究已经在观测和理论方面取得了很大的进展,但是绝大多数中等口径的太阳观测设备的高分辨率观测数据是不对外公布的,这为太阳小尺度磁结构的深入研究制造了较大的障碍。从2011年开始,云南天文台抚仙湖太阳观测站的新真空太阳望远镜(New Vacuum Solar Telescope, NVST)对太阳进行常规观测,其配备的高性能光球和色球终端设备以及即将投入使用的多通道观测终端、偏振分析器和多波段光谱仪,为我们研究太阳小尺度磁结构提供了前所未有的机遇。 本论文是将光球亮点和极区光斑两种具有千高斯量级的光球小尺度磁结构作为研究对象,使用NVST的高分辨率光球观测数据和日本国立天文台(National Astronomical Observatory of Japan, NAOJ)的极区光斑时序数据分别对它们的观测特征和统计特性进行细致的分析和研究。本论文的第一部分对太阳小尺度磁结构的研究背景、现状和意义进行了综述,并结合目前所能获取的高分辨率观测资料和长期的时间序列数据,由此提出论文的研究对象、内容和目标并展开研究。 论文的第二部分是采用NVST在TiO(氧化钛)观测波段于2012年10月29日和2013年5月21日采集的具有高时间高空间分辨率的光球观测资料,首先提出一种拉普拉斯变换和形态学膨胀相结合的识别算法来准确快速的提取出光球亮点,然后对两组观测数据进行详细的对比分析,并得出光球亮点的尺度、亮度、速度和形状等多种特征参数,最后对这些观测特征的相关性进行分析讨论。研究结果表明：1)提出的识别算法可以有效的提取出光球亮点并能对其演化特性进行深入分析,而且该算法可以应用到太阳大气其它层次上具有类似特征的小尺度亮结构上；2)光球亮点的尺寸与亮度分布具有较好的相关性,这表明NVST在光球波段的观测性能达到了预期目标,也意味着TiO谱线形成于光球层较低的位置,因此光球亮点的亮度与平均光球强度的反差要小于光球中高层的对比度；3)光球亮点的速度分布和形状变化(偏心率)的相关性可能与磁流管内的物质流动有关,这对于揭示光球亮点的振荡所激发的阿尔芬波将磁能从光球向色球和日冕传输并对高层大气进行加热有着积极的意义。 论文的第三部分是结合传统的线性分析工具和先进的非线性分析技术来研究极区光斑和黑子活动的长期时序数据的统计特性,主要是探索太阳高纬和低纬区域活动指标的周期演化、相位异步、空间分布和混沌分形等特征的异同性。研究结果表明：1)极区光斑在高频范围内的准周期数量多于低频范围内的数量,而且两个半球上的准周期值存在细微的差别,可能是由太阳活动的空间分布特性引起的；2)太阳高纬指数与低纬活动指标存在半个活动周的相位异步关系,但是在太阳活动周的不同相和不同半球上的表现并不一致；3)两者的空间分布都存在半球不同时性和不对称性,但是在不同的纬度区域表现出完全不同的特征；4)两者具有类似的低维混沌效应,但是分形维数与长程相关性略有不同,意味着它们在太阳活动中短期预报的准确性方面是不同的。这些分析结果都表明两者所表征的不同磁场本质是导致它们的统计特征既存在相似性又存在差异性的主要原因。 由于太阳小尺度磁结构在揭示太阳物理领域中多个还未完全理解的物理机制方面占有重要的科学地位,因此对其观测特性和物理机制的探索将是一项在未来很长一段时间内仍需不断研究的课题内容。针对光球亮点和极区光斑这两种具有强磁场强度的小尺度亮结构,以后将对光球亮点的磁场复杂性和自相似性、活动周演化特性、振荡行为和物质流动,并对高纬活动现象的极向漂移速率、光斑和亮点的交叉对比、光斑和谱斑的振荡异同性等方面展开后续研究。相信这些研究工作对于约束太阳湍流发电机理论、认识高层大气的加热机制和探索快速太阳风的起源等领域具有重要的推动作用。 |
| 其他摘要 | Solar magnetic structures in the solar different atmospheres exhibit a variety of spatial scales. Magnetic fields in the lower solar atmosphere have structure on the smallest observable scales (magnetic element), up to the diffraction limit of the best telescopes all over the world. Theoretical arguments and simulations indicate that there is magnetic structure well beyond what we can be observed now or in the forseeable future. Small-scale magnetic structures on the solar atmospheres can be detected almost everywhere, but they are not absolutely uniform distribution in the solar surface. Aside from they have several basic features, such as small scale, changing shape and shorter lifetime, they also have many other characteristics, e.g. rapid emergence, evolution and disappearance, they can provide most of the energy sources of solar radiation. These facts make the small-scale magnetic structures in the solar atmospheres potentially important to understand the solar global/local dynamo theory, chromospheric and coronal heating, the source and acceleration of the fast solar wind, emergence and cancellation of magnetic flux, etc., which are not fully understood today. During the last five decades, studies on the small-scale magnetic structures are one of the most important topics in solar physics. Although investigations of both observational characteristics and physical mechanism have achieved a significant progress, while a clear majority of high-resolution observations derived from medium-aperture solar telescopes can not publically downloaded. At the beginning of 2011, the New Vacuum Solar Telescope (NVST), located at Fuxian Solar Observatory of Yunnan Observatories, was successfully established. The high-performance photospheric and chromospheric observational equipments, the multi-channel observations terminals, polarimeter and multi-wavelength spectrometer open a best opportunity to study the small-scale magnetic structures. This thesis takes the magnetic bright points and polar faculae as the subject investigated, both of them have the kilo-Guass magnetic field strength. We perform a panoramic and depth exploration on both observational characteristics and statistical properties of these two small-scale structures. The first part of the thesis is an overview of background, status and significance, from which the motivation, contents and objectives of our work is introduced. In the second part, we use the high-resolution observational data derived from NVST at TiO-band on October 29, 2012 and May 21, 2013 to obtain the size, intensity, velocity and shape of magnetic bright points, and then we will analyse and discuss the observational characteristics of these two data sets. For identify the magnetic bright points, an automatic algorithm, employing Laplacian and morphological dilation technique, is proposed. Analysis results indicate that our algorithm can detect and extract bright points automatically and effectively, furthermore , it can use to recognize similar bright structures in other atmospheric layers. The size distribution of bright points is highly correlation with their intensity variation, implying that the observational performance at photospheric-band of NVST achieve its expectation aim. The correlation of velocity distribution and shape variation is related to the down-flow or up-flow of material in the magnetic flux tubes. It is useful for revealing the chromospheric and coronal heating problem which is caused by the Alfven waves excited from the oscillation of bright points. In the third part, we apply several nonlinear analysis approaches to compare the statistical properties of polar faculae and sunspot activity. Our main aim is to explore the statistical similarities of periodic variation, phase asynchronous, spatial distribution, chaotic and fractal features of solar activities at high- and low-latitudes. Analysis results show that polar faculae and sunspot activity are anti-phase, and the |
| 学科领域 | 天文学
|
| 页数 | 132
|
| 语种 | 中文
|
| 文献类型 | 学位论文
|
| 条目标识符 | http://ir.ynao.ac.cn/handle/114a53/4913
|
| 专题 | 抚仙湖太阳观测和研究基地
|
推荐引用方式
GB/T 7714 |
邓林华. 太阳小尺度结构的观测特征及物理机制的研究[D]. 北京. 中国科学院研究生院（云南天文台）,2014.
|
修改评论