One-Dimentional Numerical MHD Simulation of the Shock Events in the Outer Heliosphere
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摘要: “旅行者1号”在2012年8月穿越日球层顶后连续探测到了星际磁场的局地突然变化，通常被认为对应于激波事件，且为太阳风事件向外传播后形成的大尺度结构与日球层顶相互作用的产物。但由于观测的限制，日球层内的太阳风大尺度结构与星际空间的激波事件的对应关系尚未明确。通过一个包含太阳风等离子体和星际中性原子的双流体磁流体力学数值模型检验了这种对应关系。在距日1 AU的内边界输入2010—2017年分别位于不同经度上的OMNI，STEREO A和STEREO B的太阳风观测数据，研究了这期间太阳风与星际中性原子电荷交换后在外日球层区的传播和演化，并与“旅行者1号”和“旅行者2号”的观测数据做对比。结果表明，“旅行者1号”探测的星际空间激波事件与“旅行者2号”探测到的日球层鞘区内的压力脉冲事件具有明显的关联。Abstract: Voyager 1 occasionally detected the sudden jumps of the interstellar magnetic field strength since its heliopause crossing in August, 2012. These events are believed to be the interstellar shocks, and associated with the product of the interaction between the large-scale solar wind structures and the heliopause. In this paper, this possibility is examined by means of a two-fluid magnetohydrodynamics（MHD）simulation consisting of the solar wind plasma and the interstellar neutrals. Three different solar wind observations from OMNI, STEREO A and B at a heliocentric distance of 1 au during the year 2010－2017 are used as input to the simulation, and the evolution of solar wind in the outer heliosphere is investigated after the charge-exchange between solar wind and interstellar neutrals.The numerical results are compared with the observation from the two Voyagers, showing that the shock events in the interstellar medium observed by Voyager 1 have direct linkage with the pressure pulses in the inner heliosheath detected by Voyager 2.
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Key words:
- outer heliosphere /
- shock events /
- solar wind /
- numerical MHD simulation
Highlights● It is the first time to use the solar wind data from OMNI，the spacecraft STEREO A and B orbiting the Sun conjunctly to study the evolution and propagation of the solar wind in the outer heliosphere. ● The numerical simulations have been carried out to verify the possible correspondence between the large-scale pressure pulse structure in the heliosphere and the shock event in interstellar space. -
图 2 2011—2017年采用3种不同内边界数据源的太阳风动压对比
Fig. 2 The comparision of solar wind dynamical pressure between the observation（red）and the simulations（blue）during the years 2011—2017
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