太阳小尺度结构的观测特征及物理机制的研究

发布时间：2018-06-20 14:22

本文选题：太阳磁场 + 太阳活动　；参考：《中国科学院研究生院（云南天文台）》2014年博士论文

【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。
[Abstract]:The structure of the solar magnetic field shows a variety of spatial scales on the surface of the solar surface. The diffraction limit of the most advanced solar observation equipment at home and abroad is approaching the scale range of the smallest magnetic field structure (magnetic element) predicted by the theory. The observation data and numerical simulation reveal the small scale magnetic structure in the solar surface. The ubiquitous, but not absolute, uniform distribution, these small scale magnetic structures provide most of the energy sources of solar radiation. Although they are not as spectacular as violent flare eruptions and coronal mass ejections, they cannot ignore their importance in solar physics, because they are known and revealed. The theory of global / local turbulent generators of the sun, the mechanism of chromosphere and coronal heating, the origin and acceleration of the solar wind, the emergence of magnetic flow and the field that have not been fully understood are of considerable scientific significance.
For nearly half a century, the study of the small scale magnetic structure of the sun is one of the most concerned and highly valued topics in the field of solar physics. Although the observational characteristics and the physical mechanism of the solar small scale magnetic structure have made great progress in the field of observation and theory, but the vast majority of medium caliber The high resolution observation data of the solar observation equipment are not published, which makes a big obstacle to the deep study of the solar small scale magnetic structure. Since 2011, the new New Vacuum Solar Telescope (NVST) of the sun Observatory in Fuxian Lake, Yunnan Observatory, is equipped with a regular observation of the sun. High performance photosphere and chromosphere terminal equipment, and the upcoming multichannel observation terminal, polarization analyzer and multi band spectrometer provide unprecedented opportunities for us to study the small scale magnetic structure of the sun.
In this paper, the two kinds of small scale magnetic structures with the light ball and the polar spot are taken as the research objects. The observational features and statistics of the polar region temporal data of the high resolution optical sphere of NVST and the National Observatory (National Astronomical Observatory of Japan, NAOJ) of the Japanese National Observatory (Observatory of Japan, NAOJ) are observed respectively. The first part of this paper summarizes the research background, current situation and significance of the solar small scale magnetic structure, and combines the high resolution observation data and the long time series data that can be obtained at present, and then puts forward the research object, content and goal of the paper.
The second part of the paper is a high time and high spatial resolution optical sphere observation data collected by NVST in the TiO (titanium oxide) observation band in October 29, 2012 and May 21, 2013. First, a recognition algorithm combining Laplasse transform and morphological expansion is proposed to accurately and quickly extract light bulb bright spots, and then to two groups. The observation data are compared and analyzed in detail, and a variety of characteristic parameters such as the size, brightness, speed and shape of the bright ball bright spot are obtained. Finally, the correlation of these observation features is analyzed and discussed. The results show that: 1) the recognition algorithm can effectively extract the light bulb bright spot and can analyze its evolution characteristics deeply. And the algorithm can be applied to small scale bright structures with similar characteristics at other levels of the solar atmosphere; 2) the size of the bright light bulb has a good correlation with the distribution of luminance, which indicates that the observational performance of NVST in the light sphere reaches the desired target, which means that the TiO line is formed at a lower position in the photosphere, so the light sphere is bright. The contrast between the point brightness and the average ball strength is less than the contrast in the high layer in the light sphere; 3) the correlation between the velocity distribution and the shape change (eccentricity) of the bright ball bright spot may be related to the material flow in the magnetic flow tube, which is the transfer of the magnetic energy from the photosphere to the chromosphere and corona by the Alfan wave which reveals the oscillation of the bright ball bright spot. Heating in the upper atmosphere has a positive significance.
The third part of the thesis is to study the statistical characteristics of the long term ordinal numbers of polar spot and sunspot activities based on the traditional linear analysis tools and advanced nonlinear analysis techniques, mainly to explore the similarities and differences between the periodic evolution, Phase Asynchronism, space distribution and chaotic fractal of the activity indexes of the high and low latitude regions of the sun. The results show that: 1) the quasi periodic number of the polar spot in the high frequency range is more than the number of the low frequency range, and the quasi periodic values on the two hemispheres are slightly different, which may be caused by the spatial distribution of the solar activity; 2) the phase asynchronous relationship between the high latitude index and the low latitude active index exists in the phase of a half active week. However, the performance of different phases and different hemispheres in the solar cycle is not consistent; 3) there are hemispherical dissymmetry and asymmetry in the spatial distribution of the two, but there are completely different characteristics in different latitudes; 4) the two have similar low dimensional chaotic effects, but the fractal dimension is slightly different from the long range correlation. It means that they are different in the accuracy of the short term prediction in the solar activity. These results show that the nature of the different magnetic fields characterized by the two is the main cause of the similarity and difference in their statistical characteristics.
As the solar small scale magnetic structure occupies an important scientific position in revealing many unknown physical mechanisms in the field of solar physics, the exploration of its observation and physical mechanism will be a subject that still needs to be studied for a long time in the future. Two kinds of light ball bright spots and polar spot light spots are needed. The small scale bright structure with strong magnetic field strength will follow the following aspects, such as the complexity and self similarity of the magnetic field, the evolution characteristics of the active week, the oscillating behavior and the material flow, the extreme drift rate of the high latitude activity, the cross contrast of the spot and the bright spot, the oscillation of the spot and the spectrum of the speckle and so on. Some research work plays an important role in restricting the theory of the solar turbulence generator, understanding the heating mechanism of the high atmosphere and exploring the origin of the fast solar wind.
【学位授予单位】：中国科学院研究生院（云南天文台）
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P182

【参考文献】