JpGU-AGU Joint Meeting 2017

講演情報

[JJ] 口頭発表

セッション記号 P (宇宙惑星科学) » P-PS 惑星科学

[P-PS08] [JJ] 月の科学と探査

2017年5月20日(土) 09:00 〜 10:30 102 (国際会議場 1F)

コンビーナ:長岡 央(早稲田大学理工学術院総合研究所)、諸田 智克(名古屋大学大学院環境学研究科)、西野 真木(名古屋大学宇宙地球環境研究所)、本田 親寿(会津大学)、座長:熊本 篤志(東北大学大学院理学研究科地球物理学専攻)、座長:横田 勝一郎(ISAS/JAXA)

09:00 〜 09:15

[PPS08-01] A reconsideration of the lunar wake boundary based on Kaguya observations

*Masaki N Nishino1Yoshifumi Saito2Hideo Tsunakawa3Yuki Harada4Shoichiro Yokota2Futoshi Takahashi5Masaki Matsushima3Hidetoshi Shibuya6Hisayoshi Shimizu7 (1.Institute for Space-Earth Environmental Research, Nagoya University、2.ISAS/JAXA、3.Tokyo Institute of Technology、4.Space Science Laboratory, University of California, Berkeley、5.Kyushu University、6.Kumamoto University、7.ERI, University of Tokyo)

キーワード:Lunar wake, Solar wind, Electric field, Kaguya (SELENE)

Refilling of the tenuous lunar wake by solar wind plasma has been one of the fundamental phenomena of planetary plasma sciences. Because a portion of the solar wind electrons has much higher speed than protons, it has been widely accepted that suprathermal electrons precede protons to come into the wake along the interplanetary magnetic field. In this model, ambipolar (inward) electric fields around the wake boundary generated by the charge separation attract the surrounding solar wind protons into the central lunar wake. However, such treatment has implicitly assumed one-dimensional motion of the solar wind plasma along the magnetic field perpendicular to the solar wind flow. Here we propose a new model of the wake boundary close to the Moon, based on Kaguya observations in orbit around the Moon; Solar wind protons come into the lunar wake owing to their gyro motion and large inertia without help of suprathermal electrons, and those protons form positively charged regions and outward electric fields around the wake boundary that should attract surrounding solar wind electrons. This new model well explains electron signatures around the wake boundary detected by Kaguya at ~100 km altitude from the lunar surface.