Effect of the solar wind proton entry into the deepest lunar wake

M. N. Nishino, M. Fujimoto, Y. Saito, S. Yokota, Y. Kasahara, Y. Omura, Y. Goto, K. Hashimoto, A. Kumamoto, T. Ono, H. Tsunakawa, M. Matsushima, F. Takahashi, H. Shibuya, H. Shimizu, T. Terasawa

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

We study effect of the solar wind (SW) proton entry deep into the near-Moon wake that was recently discovered by the SELENE mission. Because previous lunar-wake models are based on electron dominance, no effect of SW proton entry has been taken into account. We show that the type-II entry of SW protons forms proton-governed region (PGR) to drastically change the electromagnetic environment of the lunar wake. Broadband electrostatic noise found in the PGR is manifestation of electron two-stream instability, which is attributed to the counter-streaming electrons attracted from the ambient SW to maintain the quasineutrality. Acceleration of the absorbed electrons up to ∼1 keV means a superabundance of positive charges of 10-510-7 cm -3 in the near-Moon wake, which should be immediately canceled out by the incoming high-speed electrons. This is a general phenomenon in the lunar wake, because PGR does not necessarily require peculiar SW conditions for its formation.

Original languageEnglish
Article numberL12106
JournalGeophysical Research Letters
Volume37
Issue number12
DOIs
Publication statusPublished - 2010 Jun

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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