Heliosphere Responds to a Large Solar Wind Intensification: Decisive Observations from IBEX
Heliosphere Responds to a Large Solar Wind Intensification: Decisive Observations from IBEX
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日光层对太阳风大幅增强的反应：IBEX 的决定性观测
DOI：
10.3847/2041-8213/aab611
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
E. Zirnstein
中科院分区：
文献类型：
--
作者：
D. McComas;M. Dayeh;H. Funsten;J. Heerikhuisen;P. Janzen;D. Reisenfeld;N. Schwadron;J. Szalay;E. Zirnstein
我们的日球层--由太阳外流的太阳风产生的局部星际介质中的气泡--终于在2014年下半年对太阳风输出和压力的大幅增加做出了反应。美国航天局的星际边界探测器（IBEX）使命任务通过观测从日鞘返回的高能中性原子（ENA）来远程监测外日球层，日鞘是终端激波和日球层顶之间的区域。IBEX观察到，从2016年底开始，高能ENA显着增强。虽然IBEX在过去十年的观测反映了ENA强度的普遍降低，表明日球层正在缩小，但新的观测表明，太阳风动压的大幅度（约50%）持续增加改变了日鞘，导致ENA排放量增加。这些新的观测结果与模拟结果相结合表明，这种压力正在重新扩大我们的日光层，终止激波和日光层顶已经在最接近太阳的位置向外驱动。IBEX观测、旅行者2号观察到的大幅瞬时压力增强和模拟之间的时间表明，压力增加通过日鞘传播，从日球顶反射，并且太阳风密度增强填充了其后面的日鞘，然后产生显着增强的ENA排放。在未来几年里，异常宇宙射线、银河宇宙辐射和星际中性原子过滤到内日球层的现象将发生重大变化。
Our heliosphere—the bubble in the local interstellar medium produced by the Sun’s outflowing solar wind—has finally responded to a large increase in solar wind output and pressure in the second half of 2014. NASA’s Interstellar Boundary Explorer (IBEX) mission remotely monitors the outer heliosphere by observing energetic neutral atoms (ENAs) returning from the heliosheath, the region between the termination shock and heliopause. IBEX observed a significant enhancement in higher energy ENAs starting in late 2016. While IBEX observations over the previous decade reflected a general reduction of ENA intensities, indicative of a deflating heliosphere, new observations show that the large (∼50%), persistent increase in the solar wind dynamic pressure has modified the heliosheath, producing enhanced ENA emissions. The combination of these new observations with simulation results indicate that this pressure is re-expanding our heliosphere, with the termination shock and heliopause already driven outward in the locations closest to the Sun. The timing between the IBEX observations, a large transient pressure enhancement seen by Voyager 2, and the simulations indicates that the pressure increase propagated through the heliosheath, reflected off the heliopause, and the enhanced density of the solar wind filled the heliosheath behind it before generating significantly enhanced ENA emissions. The coming years should see significant changes in anomalous cosmic rays, galactic cosmic radiation, and the filtration of interstellar neutral atoms into the inner heliosphere.