Solar cycle dependence of the heliospheric shape deduced from a global MHD simulation of the interaction process between a nonuniform time‐dependent solar wind and the local interstellar medium
Solar cycle dependence of the heliospheric shape deduced from a global MHD simulation of the interaction process between a nonuniform time‐dependent solar wind and the local interstellar medium
复制标题
通过对非均匀时间依赖性太阳风与当地星际介质之间相互作用过程的全球 MHD 模拟推导出太阳周期对日光层形状的依赖性
DOI：
10.1029/1999ja900011
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发表时间：
1999
影响因子：
--
通讯作者：
H. Washimi
中科院分区：
文献类型：
--
作者：
T. Tanaka;H. Washimi
本文用全三维时变磁流体动力学模型研究了太阳风/非常局域星际介质相互作用的全球结构。在这个模型中，太阳风从黄道到极点的速度从400 km/s增加到800 km/s，从太阳极小值到太阳极大值的低-高速边界的日纬度从30°变化到80°。此外，行星际磁场（IMF）在太阳活动极大期改变其极性。总体上，由于两极的太阳风冲压压力很高，终端激波（TS）和日球顶（HP）的形状沿太阳极轴沿着拉长。在黄道面，日光层结构在整个太阳活动周期中变化不大。该平面中的TS显示出特征性的子弹形结构。另一方面，在极平面上，TS的形状根据太阳活动周期的阶段呈现出许多特定的结构。这些结构包括多边形配置的极TS看到周围的太阳能最小，梅萨和梯田形TS在高速和低速太阳风区域看到周围的上升阶段，和烟囱形TS在高速太阳风区域看到周围的太阳能最大。这些结构是由直角激波、斜激波和陡斜激波的不同组合形成的，以便最有效地将日鞘等离子体输送到日尾（HT）。在HT中，来自高日纬度TS的热的弱磁化等离子体侵入远至黄道面。HT中的弱时间依赖性再循环流是侵入流的表现。HT中的磁场分布是几个太阳活动周压缩的IMF的堆积，被来自高日纬度的气流所改变。
The global structure of the solar wind/very local interstellar medium interaction is studied from a fully three-dimensional time-dependent magnetohydrodynamic model, in which the solar wind speed increases from 400 to 800 km/s in going from the ecliptic to pole and the heliolatitude of the low-high-speed boundary changes from 30° to 80° in going from the solar minimum to solar maximum. In addition, the interplanetary magnetic field (IMF) changes its polarity at the solar maximum. As a whole, the shapes of the terminal shock (TS) and heliopause (HP) are elongated along the solar polar axis owing to a high solar wind ram pressure over the poles. In the ecliptic plane, the heliospheric structure changes little throughout a solar cycle. The TS in this plane shows a characteristic bullet-shaped structure. In the polar plane, on the other hand, the shape of the TS exhibits many specific structures according to the stage of the solar cycle. These structures include the polygonal configuration of the polar TS seen around the solar minimum, the mesa- and terrace-shaped TSs in the high- and low-speed solar wind regions seen around the ascending phase, and the chimney-shaped TS in the high-speed solar wind region seen around the solar maximum. These structures are formed from different combinations of right-angle shock, oblique shock, and steep oblique shock so as to transport the heliosheath plasma most efficiently toward the heliotail (HT). In the HT, the hot and weakly-magnetized plasma from the high-heliolatitude TS invades as far as the ecliptic plane. A weakly time-dependent recirculation flow in the HT is a manifestation of invading flow. Distributions of magnetic field in the HT, which are a pile-up of the compressed IMF over several solar cycles, are modified by the flow from high-heliolatitude.