Coronal mass ejection hits mercury: AIKEF hybrid-code results compared to MESSENGER data
Coronal mass ejection hits mercury: AIKEF hybrid-code results compared to MESSENGER data
复制标题
DOI：
10.1016/j.pss.2017.12.016
复制
发表时间：
2018-04-01
影响因子：
2.4
通讯作者：
Shibayama, T.
中科院分区：
文献类型：
--
作者：
Exner, W.;Heyner, D.;Shibayama, T.
水星是最接近太阳的轨道行星，因此嵌入在强烈和高度变化的太阳风中。信使号飞船在水星附近等离子体环境的现场数据表明，2011年11月23日，一次日冕物质抛射（CME）在信使号12小时轨道的跨度上经过了水星。Slavin等人（2014年）推导出了在该轨道运行时太阳风的上游参数，并能够解释在信使轨道的尖点和磁层顶段观测到的信使数据。这些上游参数将用于第一次模拟运行。我们使用混合代码A.I.K.E.F.将离子视为单个粒子，将电子视为无质量流体，对水星磁层对CME对离子陀螺仪时间尺度的影响进行混合模拟。从模拟结果是一致的磁场测量从内日侧磁层和弓激波区。然而，在水星的夜面，水星的等离子体环境似乎是由不同的太阳风条件，总之，水星与日冕物质抛射的相互作用是不足以描述只有一套上游参数。因此，为了模拟MESSENGER位于尾部区域时的磁层响应，我们使用从MHD太阳风模拟代码SUSANOO（Shiota等人（2014））获得的参数进行第二次模拟运行。SUSANOO模型的参数实现了很好的协议的数据有关的等离子体高越和夜侧的方法来水星。然而，极地和最近的方法很难描述两个上游参数，即，上游数据集都不能重现信使穿越水星的磁层尖。我们的结论是，各自的日冕物质抛射太多变的信使轨道的时间尺度上描述只有两套上游条件。我们的研究结果表明，当地强大的和高度可变的动态的日冕物质抛射的时间尺度为15分钟，而信使是接近最接近的方法。
Mercury is the closest orbiting planet around the sun and is therefore embedded in an intensive and highly varying solar wind. In-situ data from the MESSENGER spacecraft of the plasma environment near Mercury indicates that a coronal mass ejection (CME) passed the planet on 23 November 2011 over the span of the 12 h MESSENGER orbit. Slavin et al. (2014) derived the upstream parameters of the solar wind at the time of that orbit, and were able to explain the observed MESSENGER data in the cusp and magnetopause segments of MESSENGER's trajectory. These upstream parameters will be used for our first simulation run. We use the hybrid code A.I.K.E.F. which treats ions as individual particles and electrons as a mass-less fluid, to conduct hybrid simulations of Mercury's magnetospheric response to the impact of the CME on ion gyro time scales. Results from the simulation are in agreement with magnetic field measurements from the inner day-side magnetosphere and the bow-shock region. However, at the planet's nightside, Mercury's plasma environment seemed to be governed by different solar wind conditions, in conclusion, Mercury's interaction with the CME is not sufficiently describable by only one set of upstream parameters. Therefore, to simulate the magnetospheric response while MESSENGER was located in the tail region, we use parameters obtained from the MHD solar wind simulation code SUSANOO (Shiota et al. (2014)) for our second simulation run. The parameters of the SUSANOO model achieve a good agreement of the data concerning the plasma tall crossing and the night-side approach to Mercury. However, the polar and closest approach are hardly described by both upstream parameters, namely, neither upstream dataset is able to reproduce the MESSENGER crossing of Mercury's magnetospheric cusp. We conclude that the respective CME was too variable on the timescale of the MESSENGER orbit to be described by only two sets of upstream conditions. Our results suggest locally strong and highly variable dynamics of the CME on timescales of 15 min while MESSENGER was near closest approach.