日冕物质抛射源区矢量磁场特征研究

Coronal mass ejection (CME) can release a large amount of matter to the interplanetary space in a short time. It is one of the main drivers for space weather events. The energy of CMEs is generally considered to be from magnetic fields. However, the vector magnetic field of CMEs has been less studied compared to that of solar flares. The crucial processes of the generation and propagation of CMEs as well as its relationship with solar flares remain largely unknown. Therefore, we propose here to study the vector magnetic fields in the source regions of the major flares (M-class and X-class) related CME events in the current solar cycle 24, by exploiting the latest solar full-disk vector magnetic field observations as well as complementary extreme ultraviolet multi-view and multi-band satellite data. We will use non-potential parametric analysis, non-linear force-free field extrapolations, and CME three-dimensional reconstructions to analysis the data. The first half of the proposed research is to study if there is a difference in vector magnetic fields between regions with both CMEs and X-class flares and other regions with X-class flares but no CMEs. In the second half of the proposed research, we will study the typical characteristics of vector magnetic fields in CMEs regions associated with different flare levels, by including both X- and M-class flares. Our study will generate quantitative characterization on the distribution and evolution of vector magnetic fields in CME source regions. This result would drive a deeper understanding on the relationship between CME events and solar flares, and provide strong observational constrains on current CME models.

日冕物质抛射(Coronal Mass Ejection，简称CME)可在短时间内将大量物质抛向行星际空间，是空间天气事件的主要驱动源之一。通常认为CME的能量来源于磁场，但与耀斑相比CME矢量磁场研究较少，在CME产生和传播过程、CME与耀斑的关系等方面仍有未解决的关键问题。因此，本项目拟采用最新的全日面矢量磁场观测，结合极紫外多波段、多视角卫星数据，利用非势性参数分析、非线性无力场外推、CME三维重构等手段，对目前的第24太阳活动周大耀斑（M级和X级）相关的CME事件源区进行分析。首先对X级耀斑相关的CME事件进行研究，寻找同时产生X级耀斑和CME的磁场结构与有X级耀斑却没有CME的磁场结构之间的不同点；随后将样本扩大到M级耀斑， 研究不同级别耀斑相关的CME源区的典型磁场特征。本项目关于源区矢量磁场特征分布和演化的定量结果可以加深对CME与耀斑关系的理解，约束和验证现有的CME模型。

日冕物质抛射(CME)是太阳大气中极为剧烈的大尺度爆发现象，是空间天气事件的主要驱动源之一，可能会对航天器、电网、输油管线等造成威胁。CME预报是空间天气预报的一个重要但是相对薄弱的环节。要想有效的预报CME，就要知道它从何处来，即对其位于太阳大气中的源区进行观测和分析，尤其是对源区极紫外图像和磁场等特征进行研究。本项目对第二十四太阳活动周一些对地影响较大的CME事件进行了分析，并对CME相关的活动现象，尤其是太阳耀斑和活动区演化进行了研究；我们使用SDO卫星高质量数据对20个X级耀斑的耀斑后环中的极紫外暗特征的观测性质进行了详细的研究；我们通过对活动区12673磁场演化的分析，提出了阻致爆发模型。我们对完整的第二十三太阳活动周太阳光球电流螺度与CME产生率之间的关系进行了统计研究，从太阳全球尺度研究磁场对CME产生的重要作用。我们将研究扩展至空间天气领域，采用白谱法研究地磁暴对地球电离层整体和局部的扰动过程，设计和使用太阳天气图对包括CME在内的太阳整体活动态势进行分析。在本项目执行期内，我们发表了七篇学术论文，有一名项目组成员取得硕士学位。本项目的研究有助于进一步理解CME、耀斑等活动现象的物理机制，从而提高空间天气预报水平。