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Does Magnetic Reconnection Occur in the Near Lunar Surface Environment?
Journal article   Open access   Peer reviewed

Does Magnetic Reconnection Occur in the Near Lunar Surface Environment?

Rhyan P Sawyer, J. S. Halekas, J. W. Bonnell, L. J. Chen, J. McFadden, K. H. Glassmeier, Y. Harada and A. Stanier
Geophysical research letters, Vol.50(16), e2023GL104733
08/28/2023
DOI: 10.1029/2023GL104733
url
https://doi.org/10.1029/2023GL104733View
Published (Version of record) Open Access

Abstract

The near lunar surface contains small‐scale magnetic field structures that provide a natural test bed for observing plasmas with a non‐zero Hall electric field, as well as potentially facilitating electron‐only reconnection. This study presents observational evidence of magnetized electrons as well as demagnetized ions when THEMIS‐ARTEMIS probe B reached an altitude of ∼15 km above the lunar surface. Additionally, observations suggest the presence of a field line topology change and traversal of a closed magnetic field structure containing solar wind electrons, suggestive of magnetic reconnection having occurred at some point between the solar wind interplanetary magnetic field and a lunar crustal magnetic field. Thus, the observations presented here are consistent with previous studies that predict prominent Hall electric fields near lunar crustal magnetic fields and further suggest that the solar wind interplanetary magnetic field may reconnect with lunar crustal magnetic fields, most likely via electron‐only reconnection. Plain Language Summary While interactions between the solar wind and the Earth's magnetosphere have been well studied, there is still much to be learned by studying the interactions between the solar wind and the small‐scale lunar magnetic fields. Due to the small‐scale nature of the lunar magnetic fields, previous studies have suggested that the ions do not respond in the same manner as the electrons. The resulting effects lead to an electric field near regions of lunar magnetic fields. This study presents observational evidence of the aforementioned phenomena. Additionally, the spacecraft observations also suggest that magnetic reconnection, or the breaking of the lunar magnetic field lines and reconnection to the magnetic field in the solar wind, was occurring between the solar wind and the lunar magnetic fields. Key Points Observations suggest magnetic reconnection occurs between the solar wind IMF and lunar crustal magnetic fields Electron pitch angle and velocity distributions suggest the spacecraft traversed a closed magnetic topology containing solar wind electrons We report in‐situ observations of demagnetized ions and associated Hall electric fields near the lunar surface
lunar crustal magnetic fields magnetic reconnection solar wind interactions UIOWA OA Agreement

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