Variability of the Interplanetary Magnetic Field as a Driver of Electromagnetic Induction in Mercury's Interior
Variability of the Interplanetary Magnetic Field as a Driver of Electromagnetic Induction in Mercury's Interior
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DOI：
10.1029/2021ja029664
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发表时间：
2021-03
期刊：
影响因子：
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通讯作者：
S. Zomerdijk‐Russell;A. Masters;D. Heyner
中科院分区：
文献类型：
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作者：
S. Zomerdijk‐Russell;A. Masters;D. Heyner
水星的磁层是一个独特的动态系统，主要是因为水星靠近太阳，而且体积很小。太阳风和嵌入行星际磁场（IMF）和昼侧Hermean磁层之间的相互作用驱动系统的磁层顶边界上的电流。到目前为止，由于磁层顶运动对外部压力变化的反应而产生的电磁感应已经被用来限制水星的铁核大小。在这里，我们评估的影响，不断变化的IMF方向上的Hermean磁层顶电流，以及由此产生的感应磁场。水星表面，空间ENERGY，地球化学和测距（信使号）航天器在第一个“热季”的昼侧磁层顶边界过境点的观测，被用来证明货币基金组织的方向水星的磁层顶电流的重要性。我们的16个边界穿越表明，与只考虑内部行星场的情况相比，外部IMF的引入使磁层顶电流方向改变了10°至100°。分析模型被用来填补更大的画面，并建议IMF的东西方向反转，典型的日光层电流片扫过水星的磁层，在水星表面的感应场所产生的磁层顶电流动态是在全球行星场的30%的顺序。这些结果表明，IMF的变化单独对水星的磁层顶电流有明显的影响，并在行星周围产生了显着的感应磁场。BepiColombo使命的到来将使这种反应作为探测水星内部的一种方法得到进一步探索。
Mercury's magnetosphere is a unique and dynamic system, primarily due to the proximity of the planet to the Sun and its small size. Interactions between solar wind and embedded interplanetary magnetic field (IMF) and the dayside Hermean magnetosphere drive an electric current on the system's magnetopause boundary. So far, electromagnetic induction due to magnetopause motion in response to changing external pressure has been used to constrain Mercury's iron core size. Here we assess the impact a changing IMF direction has on the Hermean magnetopause currents, and the resulting inducing magnetic field. Observations made by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft during dayside magnetopause boundary crossings in the first “hot season,” are used to demonstrate the importance of the IMF direction to Mercury's magnetopause currents. Our 16 boundary crossings show that introduction of external IMFs change the magnetopause current direction by 10° to 100°, compared to the case where only the internal planetary field is considered. Analytical modeling was used to fill in the bigger picture and suggests for an east‐west reversal of the IMF, typical of the heliospheric current sheet sweeping over Mercury's magnetosphere, the inducing field at Mercury's surface caused by the resulting magnetopause current dynamics is on the order of 30% of the global planetary field. These results suggest that IMF variability alone has an appreciable effect on Mercury's magnetopause current and generates a significant inducing magnetic field around the planet. The arrival of the BepiColombo mission will allow this response to be further explored as a method of probing Mercury's interior.