Anomalous deformation of the Earth's bow shock in the lunar wake: Joint measurement by Chang'E-1 and SELENE

Masaki N. Nishino, Xiao Dong Wang, Masaki Fujimoto, Hideo Tsunakawa, Yoshifumi Saito, Shoichiro Yokota, Wei Bian, Chun Lai Li, Masaki Matsushima, Hidetoshi Shibuya, Hisayoshi Shimizu, Futoshi Takahashi, Toshio Terasawa

研究成果: Contribution to journalArticle査読

10 被引用数 (Scopus)


Because the solar wind (SW) flow is usually super-sonic, a fast-mode bow shock (BS) is formed in front of the Earth's magnetosphere, and the Moon crosses the BS at both dusk and dawn flanks. On the other hand, behind of the Moon along the SW flow forms a tenuous region called lunar wake, where the flow can be sub-Alfvnic (and thus sub-sonic) because of its low-density status. Here we report, with joint measurement by Chang'E-1 and SELENE, that the Earth's BS surface is drastically deformed in the lunar wake. Despite the quasi-perpendicular shock configuration encountered at dusk flank under the Parker-spiral magnetic field, no clear shock surface can be found in the lunar wake, while instead gradual transition of the magnetic field from the upstream to downstream value was observed for a several-minute interval. This finding suggests that the 'magnetic ramp' is highly broadened in the wake where a fast-mode shock is no longer maintained due to the highly reduced density. On the other hand, observations at the 100 km altitude on the dayside show that the fast-mode shock is maintained even when the width of the downstream region is smaller than a typical scale length of a perpendicular shock. Our results suggest that the Moon is not so large to eliminate the BS at 100 km altitude on the dayside, while the magnetic field associated with the shock structure is drastically affected in the lunar wake.

ジャーナルPlanetary and Space Science
出版ステータス出版済み - 4 2011

All Science Journal Classification (ASJC) codes

  • 天文学と天体物理学
  • 宇宙惑星科学


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