論文

査読有り
2017年9月

Kaguya observations of the lunar wake in the terrestrial foreshock: Surface potential change by bow-shock reflected ions

ICARUS
  • Masaki N. Nishino
  • ,
  • Yuki Harada
  • ,
  • Yoshifumi Saito
  • ,
  • Hideo Tsunakawa
  • ,
  • Futoshi Takahashi
  • ,
  • Shoichiro Yokota
  • ,
  • Masaki Matsushima
  • ,
  • Hidetoshi Shibuya
  • ,
  • Hisayoshi Shimizu

293
開始ページ
45
終了ページ
51
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1016/j.icarus.2017.04.005
出版者・発行元
ACADEMIC PRESS INC ELSEVIER SCIENCE

There forms a tenuous region called the wake behind the Moon in the solar wind, and plasma entry/refilling into the wake is a fundamental problem of the lunar plasma science. High-energy ions and electrons in the foreshock of the Earth's magnetosphere were detected at the lunar surface in the Apollo era, but their effects on the lunar night-side environment have never been studied. Here we show the first observation of bow-shock reflected protons by Kaguya (SELENE) spacecraft in orbit around the Moon, confirming that solar wind plasma reflected at the terrestrial bow shock can easily access the deepest lunar wake when the Moon stays in the foreshock (We name this mechanism type-3 entry'). In a continuous type-3 event, low-energy electron beams from the lunar night-side surface are not obvious even though the spacecraft location is magnetically connected to the lunar surface. On the other hand, in an intermittent type-3 entry event, the kinetic energy of upward-going field-aligned electron beams decreases from similar to 80 eV to similar to 20 eV or electron beams disappear as the bow-shock reflected ions come accompanied by enhanced downward electrons. According to theoretical treatment based on electric current balance at the lunar surface including secondary electron emission by incident electron and ion impact, we deduce that incident ions would be accompanied by a few to several times higher flux of an incident electron flux, which well fits observed downward fluxes. We conclude that impact by the bow-shock reflected ions and electrons raises the electrostatic potential of the lunar night-side surface. (C) 2017 Elsevier Inc. All rights reserved.

リンク情報
DOI
https://doi.org/10.1016/j.icarus.2017.04.005
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000402849700004&DestApp=WOS_CPL
ID情報
  • DOI : 10.1016/j.icarus.2017.04.005
  • ISSN : 0019-1035
  • eISSN : 1090-2643
  • Web of Science ID : WOS:000402849700004

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