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Solar‐wind proton access deep into the near‐Moon wake
Author(s) -
Nishino M. N.,
Fujimoto M.,
Maezawa K.,
Saito Y.,
Yokota S.,
Asamura K.,
Tanaka T.,
Tsunakawa H.,
Matsushima M.,
Takahashi F.,
Terasawa T.,
Shibuya H.,
Shimizu H.
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl039444
Subject(s) - wake , solar wind , physics , proton , geology , geophysics , plasma , thermodynamics , quantum mechanics
We study solar wind (SW) entry deep into the near‐Moon wake using SELENE (KAGUYA) data. It has been known that SW protons flowing around the Moon access the central region of the distant lunar wake, while their intrusion deep into the near‐Moon wake has never been expected. We show that SW protons sneak into the deepest lunar wake (anti‐subsolar region at ∼100 km altitude), and that the entry yields strong asymmetry of the near‐Moon wake environment. Particle trajectory calculations demonstrate that these SW protons are once scattered at the lunar dayside surface, picked‐up by the SW motional electric field, and finally sneak into the deepest wake. Our results mean that the SW protons scattered at the lunar dayside surface and coming into the night side region are crucial for plasma environment in the wake, suggesting absorption of ambient SW electrons into the wake to maintain quasi‐neutrality.