SELENE観測データに基づく月ウェイク領域プラズマ環境の解明

2009 Fiscal Year Annual Research Report

• Project/Area Number: 21740359
• Research Institution: Japan Aerospace Exploration Agency
• Principal Investigator: 西野 真木 Japan Aerospace Exploration Agency, 宇宙科学研究本部, 研究員 (50466794)
• Keywords: 月ウェイク / SELENE / 太陽風

Research Abstract

月周回衛星SELENEによる観測データを用い、下記の事柄を明らかにした。
(1) 月表面近くのウェイク領域に太陽風プロトンがエネルギー増減を伴いながら侵入する(I型侵入)
(2) 月の昼間側で反射したプロトンが月ウェイクの最深部に侵入する(II型侵入)
I型侵入は、惑星間空間磁場のBYまたはBZ成分(太陽風の流れに垂直な成分)の符号に依存して発生する。このメカニズムにより、過去の研究では太陽風プロトンが侵入しないと考えられてきた領域(100km高度、太陽天頂角150度)まで太陽風が侵入することが分かった。
II型侵入の発生も惑星間空間磁場の垂直成分に依存するが、I型とは発生機構が異なる。I型は太陽風プロトンの熱速度により夜側に直接侵入するが、II型は月の昼間側に衝突・反射したプロトンが自己ピックアップ加速を受けることにより加速され、月半径程度の大きなジャイロ半径を持つことによって夜側最深部に侵入する。
これらの成果は、これまでの「月ウェイクの電磁気環境は太陽風の電子によって支配される」という考えを覆し、イオンも月ウェイクの環境に非常に寄与することを示している。

Research Products

• [Journal Article] Pairwise energy gain-loss feature of solar wind protons in the near-Moon wake (2009)
  • Author(s): Nishino, M.N., K.Maezawa, M.Fujimoto, Y.Saito, S.Yokota, K.Asamura, T.Tanaka, H.Tsunakawa, M.Matsushima, F.Takahashi, T.Terasawa, H.Shibuya, H.Shimizu
  • Journal Title: Geophysical Research Letters 36 Pages: L12108
  • Peer Reviewed
• [Journal Article] Solar-wind proton access deep into the near-Moon wake (2009)
  • Author(s): Nishino, M.N., M.Fujimoto, K.Maezawa, Y.Saito, S.Yokota, K.Asamura, T.Tanaka, H.Tsunakawa, M.Matsushima, F.Takahashi, T.Terasawa, H.Shibuya, H.Shimizu
  • Journal Title: Geophysical Research Letters 36 Pages: L16103
  • Peer Reviewed
• [Journal Article] Plasma environment of the lunar wake observed by SELENE-MAP (2009)
  • Author(s): Nishino, M.N., M.Fujimoto, Y.Saito, S.Yokota, K.Asamura, T.Tanaka, H.Tsunakawa, H.Shibuya, M.Matsushima, H.Shimizu, F.Takahashi, T.Terasawa, SELENE MAP Team
  • Journal Title: Proceedings of the ISAS lunar and planetary symposium 41 Pages: AA0064291012
• [Presentation] Effect of the solar wind entry into the deepest lunar wake (2010)
  • Author(s): Masaki N.Nishino, Masaki Fujimoto, Yoshifumi Saito, Shoichiro Yokota, Yoshiya Kasahara, Yoshiharu Omura, Yoshitaka Goto, Kozo Hashimoto, Atsushi Kumamoto, Takayuki Ono, Hideo Tsunakawa, Masaki Matsushima, Futoshi Takahashi, Hidetoshi Shibuya, Hisayoshi Shimizu, Toshio Terasawa
  • Organizer: 第11回惑星圏研究会
  • Place of Presentation: 仙台市・東北大学
  • Year and Date: 2010-03-17
• [Presentation] (Invited Presentation) Intrusion of the solar wind protons into the near-Moonwake revealed by SELENE (KAGUYA) (2009)
  • Author(s): Nishino, M.N., K.Maezawa, M.Fujimoto, Y.Saito, S.Yokota, K.Asamura, T.Tanaka, H.Tsunakawa, H.Shibuya, M.Matsushima, H.Shimizu, F.Takahashi, T.Terasawa
  • Organizer: AGU Fall Meeting 2009
  • Place of Presentation: US, San Francisco, Moscone Convention Center
  • Year and Date: 2009-12-16
• [Presentation] Two mechanisms of solar-wind proton entry deep into the near-Moon wake revealed by SELENE (2009)
  • Author(s): Masaki N.Nishino, Masaki Fujimoto, Kiyoshi Maezawa, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Toshio Terasawa
  • Organizer: The Lunar Plasma Environment Science Workshop
  • Place of Presentation: 中華人民共和國澳門特別行政區・澳門科技大學
  • Year and Date: 2009-10-22
• [Presentation] Signatures of electrons and waves in the near-Moon wake (2009)
  • Author(s): Masaki N.Nishino, PACE, LMAG, LRS members
  • Organizer: The Lunar Plasma Environment Science Workshop
  • Place of Presentation: 中華人民共和國澳門特別行政區・澳門科技大學
  • Year and Date: 2009-10-22
• [Presentation] Asymmetric nightside surface charging of the Moon in the solax wind (2009)
  • Author(s): Masaki N.Nishino, Masaki Fujimoto, Kiyoshi Maezawa, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi,Toshio Terasawa
  • Organizer: 地球電磁気・地球惑星圏学会 第112回講演会
  • Place of Presentation: 金沢市・金沢大学
  • Year and Date: 2009-09-30
• [Presentation] Solar-wind proton access deep into the near-Moon wake observed by SELENE (KAGUYA) (2009)
  • Author(s): Masaki N.Nishino, Masaki Fujimoto, Kiyoshi Maezawa, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Toshio Terasawa
  • Organizer: 地球電磁気・地球惑星圏学会 第112回講演会
  • Place of Presentation: 金沢市・金沢大学
  • Year and Date: 2009-09-28
• [Presentation] Two mechanisms of solar-wind proton entry deep into the near-Moon wake revealed by SELENE (KAGUYA) (2009)
  • Author(s): Masaki N.Nishino, Masaki Fujimoto, Kiyoshi Maezawa, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Toshio Terasawa
  • Organizer: European Planetary Science Congress 2009
  • Place of Presentation: Germany, Potsdam
  • Year and Date: 2009-09-19
• [Presentation] Intrusion of the solar wind protons into the near-Moon wake observed by SELENE (KAGUYA) (2009)
  • Author(s): Masaki N.Nishino, Kiyoshi Maezawa, Masaki Fujimoto, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Toshio Terasawa, KAGUYA MAP-PACE Team, KAGUYA MAP-LMAG Team
  • Organizer: AOGS 2009
  • Place of Presentation: Suntec Singapore International Convention and Exhibition Centre
  • Year and Date: 2009-08-13
• [Presentation] Two mechanisms of solar-wind proton entry deep into the near-Moon wake revealed by SELENE (KAGUYA) (2009)
  • Author(s): Masaki N.Nishino, Masaki Fujimoto, Kiyoshi Maezawa, Yoshifumi Saito, Shoichiro Yokota, Kazushi Asamura, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Toshio Terasawa
  • Organizer: The 42nd ISAS Lunar and Planetary Symposium
  • Place of Presentation: 相模原市・宇宙科学研究本部
  • Year and Date: 2009-08-06
• [Presentation] Intrusion of the solar wind ions into the lunar low-altitude wake observed by SELENE (KAGUYA) (2009)
  • Author(s): Masaki N.Nishino, Masaki Fujimoto, Kiyoshi Maezawa, Yoshifumi Saito, Yokota shoichiro, Kazushi Asamura, Takaaki Tanaka, Hideo Tsunakawa, Hidetoshi Shibuya, Masaki Matsushima, Hisayoshi Shimizu, Futoshi Takahashi, Toshio Terasawa
  • Organizer: 地球惑星科学連合大会2009
  • Place of Presentation: 千葉市美浜区・幕張メッセ国際会議場
  • Year and Date: 2009-05-18
• [Presentation] Intrusion of the solar wind ions into the lunar low-altitude wake observed by SELENE (KAGUYA) (2009)
  • Author(s): M.N.Nishino, M.Fujimoto, K.Maezawa, Y.Saito, S.Yokota, K.Asamura, T.Tanaka, H.Tsunakawa, H.Shibuya, M.Matsushima, H.Shimizu, F.Takahashi, T.Terasawa
  • Organizer: European Geophysical Union General Meeging 2009
  • Place of Presentation: Austria, Vienna
  • Year and Date: 2009-04-23