Large-amplitude monochromatic ULF waves detected by Kaguya at the moon
Large-amplitude monochromatic ULF waves detected by Kaguya at the moon
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辉夜号在月球上探测到的大振幅单色超低频波
DOI：
10.1029/2011ja017249
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
and M. Matsushima
中科院分区：
文献类型：
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作者：
Nakagawa;T.;A. Nakayama;F. Takahashi;H. Tsunakawa;H. Shibuya;H. Shimizu;and M. Matsushima
2008年1月1日至2008年11月30日，“月亮”号上搭载的MAP/LMAG磁力计在距月球表面100公里的轨道上探测到了大振幅单色超低频波。主导频率为8.3 × 10−3 ~ 1.0 × 10−2Hz，对应的周期为120 s ~ 100 s。其振幅可达3nt。当月球处于地球弓形激波上游的太阳风中时，有10%的时间可以观测到它们。它们只有在月球轨道上的月亮女神号探测到，而在上游太阳风上的ACE没有探测到。在明暗分界线以上和日面发生率较高。传播的方向并不完全平行于行星际磁场，而是倾向于磁场方向和垂直于航天器下方月球表面的方向。磁场旋转的感觉在53%的事件中相对于磁场是左旋的，而47%的事件显示为右旋极化。可能的产生机制是磁流体动力波与月球反射的太阳风质子发生回旋共振。反射质子的能量可以解释超光速波的能量。不平行于入射太阳风流的传播方向可以解释观测到的频率和左旋和右旋极化几乎相等的百分比。
Large amplitude, monochromatic ultra low frequency (ULF) waves were detected by MAP/LMAG magnetometer onboard Kaguya during the period from 1 January 2008 to 30 November 2008 on its orbit 100 km above the lunar surface. The dominant frequency was 8.3 × 10−3– 1.0 × 10−2Hz, corresponding to the periods of 120 s – 100 s. The amplitude was as large as 3 nT. They were observed in 10% of the time when the moon was in the solar wind far upstream of the Earth's bow shock. They were detected only by Kaguya on the orbit around the moon, but not by ACE in the upstream solar wind. The occurrence rate was high above the terminator and on the dayside surface. The direction of the propagation was not exactly parallel to the interplanetary magnetic field, but showed a preference to the direction of the magnetic field and the direction perpendicular to the surface of the moon below the spacecraft. The sense of rotation of the magnetic field was left‐handed with respect to the magnetic field in 53% of the events, while 47% showed right‐handed polarization. The possible generation mechanism is the cyclotron resonance of the magnetohydrodynamic waves with the solar wind protons reflected by the moon. The energy of the reflected protons can account for the energy of the ULF waves. The propagation direction which are not parallel to the incident solar wind flow can explain the observed frequency and the nearly equal percentages of the left‐handed and right‐handed polarizations.