太阳光球和色球磁亮点的多波段观测模式与数值分析方法探讨

The heating of the solar corona to high temperatures is one of the most important problems in solar physics. Solutions have been hampered by an incomplete understanding of the magnetically controlled structures in the lower solar atmosphere. Magnetic bright points (MBPs) in the photosphere and chromosphere of the Sun, located in the dark inter-granular lanes, are ultrafine magnetic structures that are extensively used as reliable tracers for magnetic flux tubes. The rapidly transverse motions of the footpoints of photospheric MBPs are thought to be an ultimate source of the energy needed to heat the solar corona, either via waves or via magnetic reconnection of intertwined flux tubes. Based on the ultra-high-resolution ( about 0.1″-0.2″) and multi-wavelength observations with the New Vacuum Solar Telescope (NVST) and the data of both upper solar atmosphere and magnetogram provided by SDO and Hinode, we will study the high-resolution observational characteristics and physical mechanism of MBPs with the help of several image processing techniques and numerical analysis approaches. We will work on (1) selection and optimization of multi-wavelength observational modes for NVST; (2) physical similarities and distinctions of MBPs located in photosphere and chromosphere, and in the quite-Sun area, the active region, and the coronal hole; (3) turbulent diffusion, magnetic wave modes, and oscillatory behavior of photospheric and chromospheric MBPs, and obtain the qualitative and quantitative results. We aim our studies at getting better understanding about their crucial roles in the coronal heating mechanism and local turbulent dynamo, and the physical relationship between MBPs and small-scale quiet and explosive phenomena, such as spicules, microflare and nanoflare. Finally, we will evaluate the scientific status of NVST that solving the frontier and hot topics in solar physics, and will provide some observational suggestions or comments for NVST.

日冕加热机制是太阳物理领域十分重要的研究课题之一。光球和色球磁亮点是扎根于米粒暗径里的超精细磁流管结构，其足点的快速横向本征运动通过激发磁波或磁重联的方式将磁能向上传输到高层大气并加热日冕。本项目立足于NVST的高分辨多波段观测资料，结合SDO和Hinode的高层大气和磁场数据，运用多种图像处理技术和数值分析手段开展对磁亮点的高分辨观测特征研究。本项目拟在（1）NVST光球和色球的多波段观测模式和策略的选取与优化；（2）磁亮点在光球和色球多个波段、宁静区和活动区及冕洞区的物理异同性；（3）光球和色球磁亮点的湍流扩散、波动和振荡行为等方面取得定性和定量的分析结果。在此基础之上，深刻理解光球和色球磁亮点在揭示日冕加热机制和局部湍流发电机理论中的作用，探索磁亮点与色球针状体、微耀斑和纳耀斑等小尺度宁静和爆发现象的物理联系，进而评估NVST在解决太阳物理前沿热点问题中的科学地位并提供观测指导建议。

太阳低层大气中的多尺度磁结构的观测特征和驱动机制是太阳物理研究中高度重视的前沿课题之一，对揭示日冕加热机制和局部发电机理论具有十分重要的科学意义。光球和色球磁亮点是扎根于米粒暗径里的超精细磁流管结构，其足点的快速横向本征运动通过激发磁波或磁重联的方式将磁能向上传输并加热日冕。.本项目的研究内容和重要成果概括如下：（1）提出了一种基于拉普拉斯变换和形态学膨胀相结合的图像处理技术将太阳磁亮点识别出来，然后对其统计参数进行细致分析，进而对相应的观测模式和数值分析技术提供理论支持；太阳磁亮点的尺寸分布、面积分布与形态分布的曲线是类似的，但与强度变化的拟合曲线略有差别，这与强场区域抑制大气表面的磁对流效应一致。（2）由于太阳磁场活动现象在物理本质上表现出非线性和非稳定性行为，基于功能强大的非线性分析工具和太阳观测设备的长期监测资料，对太阳不同观测波段、不同尺度磁结构和不同经度纬度带的统计特征和物理机制方面取得定量分析结果，分析南北半球的空间分布特性、高纬和低纬活动的混沌分形特征等整体行为；（3）太阳耀斑现象与光球下面的新浮磁流有关，剪切和浮现被认为是一种建立磁场能量的重要方式，而且很有可能在随后发生的耀斑过程中完成释放。采用交叉递归图、误差极值重标和周期分析技术研究了太阳色球耀斑指数在南北半球上的统计差异性，主要结果包括：从全局观点来看，两个半球的耀斑指数是高度相关的，但是北半球领先南半球7个月；两个半球上均存在长程相关性，但动力复杂性略有不同。.本项目的研究成果，对于深刻理解太阳磁亮点在日冕加热机制和局部湍流发电机理论中的作用，探索磁能传输、集聚和耗散过程以及太阳活动的非线性动力学演化本质，进而深化对太阳磁场起源和演化规律的理解并评估NVST在解决太阳物理前沿热点问题中的科学地位具有显著的科学意义。