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Detection of m/q = 2 pickup ions in the plasma environment of the Moon: The trace of exospheric H 2 +
Author(s) -
Wang X.D.,
Zong Q.G.,
Wang J.S.,
Cui J.,
Rème H.,
Dandouras I.,
Aoustin C.,
Tan X.,
Shen J.,
Ren X.,
Liu J.J.,
Zuo W.,
Su Y.,
Wen W.B.,
Wang F.,
Fu Q.,
Mu L.L.,
Wang X.Q.,
Geng L.,
Zhang Z.B.,
Liu J.Z.,
Zhang H.B.,
Li C.L.,
Ouyang Z.Y.
Publication year - 2011
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 - 10.1029/2011gl047488
Subject(s) - ion , exosphere , pickup , plasma , physics , astrobiology , trace (psycholinguistics) , atomic physics , astronomy , nuclear physics , computer science , quantum mechanics , linguistics , philosophy , artificial intelligence , image (mathematics)
The Solar Wind Ion Detectors (SWIDs) on the Chang'E‐1 spacecraft, while orbiting the Moon, occasionally observed two continuous flux peaks with energies not exceeding 8 and 4 times that of the prevailing solar wind proton energy. These form parallel curves (PCs) with an energy ratio of 2 in the energy‐time spectrogram. The fluxes of the two curves are comparable, around 10 −5 ∼ 10 − 4 of the solar wind flux. The pitch angle distribution of PC particles is concentrated around 90°. The velocity space distribution of PC particles shows distinct double‐ring feature, suggesting the existence of a pickup ion species with m/q = 2. Pickup ions from local interstellar medium, the inner sources and the lunar exosphere are investigated. We conclude that this observation may be the first in situ evidence for H 2 + ions in the lunar exosphere, thus providing new insights on the evolution and fate of solar wind hydrogen in the solar system.