arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1407.4258astro-ph.SR
收藏

太阳的日冕物质抛射--传播和近地效应

Coronal Mass Ejections from the Sun - Propagation and Near Earth Effects

Arun Babu

摘要:

由于我们对空间技术的依赖,对近地空间环境干扰的认识证明越来越重要。来自太阳的地球定向日冕物质抛射(CME)是空间天气扰动的主要驱动力。因此,对日冕物质抛射、其运动学及其近地效应的研究越来越重要。CME在地球附近的影响通常表现为银河系宇宙线强度的短暂下降,这被称为福布什下降(FD)。在这篇论文中,我们使用位于Ooty的GRAPES-3 μ子望远镜的FD观测来探测CME的结构及其相关的激波。我们已经确定,银河系宇宙射线向日冕物质抛射的累积扩散是导致FD的主要机制(第3章)。这种扩散通过CME和激波之间的湍流鞘区发生。我们的主要结果之一涉及在这一地区的湍流水平。我们已经定量地建立了由磁场湍流辅助的交叉场扩散解释了所观察到的FD和鞘层区域的磁场增强之间的滞后(第4章)。在这篇论文中,我们还研究了CME的驱动力的性质。利用来自STEREO太空船上SECCHI日冕仪的CME数据,我们发现了这些CME内部磁场配置的非无力性质的证据,这是(经常被引用的)洛伦兹自作用力驱动的基础(第5章)。综上所述,本论文的工作是对日冕物质抛射从典型观测场向地球传播的一次全面的尝试。

英文摘要:

Owing to our dependance on spaceborne technology, an awareness of disturbances in the near-Earth space environment is proving to be increasingly crucial. Earth-directed Coronal mass ejections (CMEs) emanating from the Sun are the primary drivers of space weather disturbances. Studies of CMEs, their kinematics, and their near-Earth effects are therefore gaining in importance. The effect of CMEs near the Earth is often manifested as transient decreases in galactic cosmic ray intensity, which are called Forbush decreases (FDs). In this thesis we probe the structure of CMEs and their associated shocks using FD observations by the GRAPES-3 muon telescope at Ooty. We have established that the cumulative diffusion of galactic cosmic rays into the CME is the dominant mechanism for causing FDs (Chapter 3). This diffusion takes place through a turbulent sheath region between the CME and the shock. One of our main results concerns the turbulence level in this region. We have quantitatively established that cross-field diffusion aided by magnetic field turbulence accounts for the observed lag between the FD and the magnetic field enhancement of the sheath region (Chapter 4 ). We have also investigated the nature of the driving forces acting on CMEs in this thesis. Using CME data from the SECCHI coronagraphs aboard STEREO sapcecraft, we have found evidence for the non-force-free nature of the magnetic field configuration inside these CMEs, which is the basis for the (often-invoked) Lorentz self-force driving (Chapter 5). Taken together the work presented in this thesis is a comprehensive attempt to characterise CME propagation from typical coronagraph fields of view to the Earth.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑