Effects of Anomalous Cosmic Rays on the Structure of the Outer Heliosphere
Effects of Anomalous Cosmic Rays on the Structure of the Outer Heliosphere
复制标题
异常宇宙线对外日球层结构的影响
DOI：
10.3847/1538-4357/aabf42
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发表时间：
2018-06-01
影响因子：
4.9
通讯作者：
Wang, Chi
中科院分区：
文献类型：
--
作者：
Guo, Xiaocheng;Florinski, Vladimir;Wang, Chi
根据旅行者一号的观测，一些异常宇宙射线（ACR）可能已经穿过日球层顶并逃逸到星际介质中，从而提供了一种传统磁流体动力学（MHD）模型中未包含的内外日鞘之间的能量转移机制。在本文中，我们使用包含宇宙射线扩散传输的简单模型研究了高能粒子通过日球层顶逃逸对日球层大小和形状的影响。我们表明，ACR 的存在显着改变了日光层结构，包括日光层顶和终止激波的位置。研究发现，当扩散粒子的压力与等离子体背景的压力相当时，对于一定的 ACR 扩散系数值，日光层顶会收缩。航海家一号和二号在各自终止激波穿越期间对高能粒子的观测差异在这里被解释为由于太阳周期不同阶段期间扩散环境的差异所致。航海者 2 号测得的激波上游 ACR 强度增强的较短时期可能是由于与航海者 1 号穿越时间相比较弱的径向扩散传输造成的。我们得出的结论是，ACR 扩散效应可能很突出，应该包含在日光层的 MHD 模型中。
Based on Voyager 1 observations, some anomalous cosmic rays (ACRs) may have crossed the heliopause and escaped into the interstellar medium, providing a mechanism of energy transfer between the inner and outer heliosheaths that is not included in conventional magnetohydrodynamics (MHD) models. In this paper, we study the effect of energetic particles’ escape through the heliopause on the size and shape of the heliosphere using a simple model that includes diffusive transport of cosmic rays. We show that the presence of ACRs significantly changes the heliosphere structure, including the location of the heliopause and termination shock. It was found that the heliopause would contract for certain values of the ACR diffusion coefficients when the diffusive particles’ pressure is comparable to the pressure of the plasma background. The difference in Voyager 1 and 2 observations of energetic particles during their respective termination shock crossings is interpreted here as due to the differences in diffusion environments during the different phases of the solar cycle. The shorter period of enhanced ACR intensities upstream of the shock measured by Voyager 2 may have been caused by weaker radial diffusive transport compared with the time of Voyager 1 crossing. We conclude that ACR diffusive effects could be prominent and should be included in MHD models of the heliosphere.