Global Maps of Solar Wind Electron Modification by Electrostatic Waves Above the Lunar Day Side: Kaguya Observations. Issue 17 (2nd September 2021)

• Record Type: Journal Article
• Authors: Harada, Yuki; Kasahara, Yoshiya; Nishino, Masaki N.; Kurita, Satoshi; Saito, Yoshifumi; Yokota, Shoichiro; Kumamoto, Atsushi; Takahashi, Futoshi; Shimizu, Hisayoshi
• Is Part Of: Geophysical research letters. Volume 48:Issue 17(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-02
• Subjects: Moon -- Kaguya -- electrostatic waves -- electron two stream instability -- electron cyclotron drift instability; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2021GL095260
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The Moon drives observable perturbations in the upstream solar wind in a similar manner to the terrestrial foreshock. Recent observations suggested that lunar dayside electrostatic waves can arise from two different driving mechanisms, both involving reflected particles from lunar crustal magnetic fields. However, their association with the global distribution of lunar magnetic anomalies have not been fully characterized. Here we exploit polar orbiting Kaguya to generate first global maps of electrostatic waves and solar wind electron modification above the day side of the Moon. The maps clearly demonstrate that the two signatures are correlated with lunar crustal magnetic fields. Additionally, we observe different characteristics of electron modification for different interplanetary magnetic field orientations. The lunar crustal magnetic fields cause a wide range of reflected electron and ion intensities, thereby serving as a test bed to investigate the relative roles of reflected particles on wave excitation and particle heating. Plain Language Summary: The Moon drives a variety of waves in the surrounding ionized gas. In this study, we make a world map showing the population of one of these waves, electrostatic waves, on the Moon. The wave map shows a clear pattern resembling the lunar magnetic field map. This suggests that the waves are caused by reflection of charged particles from the localized magnetic field of the Moon. Additionally, we observe a change in incoming electrons from the Sun when the waves are present. Our results demonstrate that the space around the Moon is a useful place to study interactions between particles and waves, which occur in many other places in space. Key Points: We present first global maps of electrostatic waves and solar wind electron modification on the lunar day side The wave generation and resulting solar wind electron modification are clearly controlled by lunar crustal magnetic fields Two types of electron‐wave interactions are observed under different interplanetary magnetic field orientations