Lunar Magnetic Field Observation and Initial Global Mapping of Lunar Magnetic Anomalies by MAP-LMAG Onboard SELENE (Kaguya)

Tsunakawa, Hideo; Shibuya, H.; Takahashi, Futoshi; Shimizu, Hisayoshi; Matsushima, Masaki; Matsuoka, A.; Nakazawa, Shozo; Otake, Hisashi; Iijima, Y.

doi:10.1007/s11214-010-9652-0

Cited by 108 publications

(102 citation statements)

References 51 publications

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“…The lunar magnetometer (LMAG) on Kaguya measured the magnetic field vectors at a sampling rate of 32 Hz (Tsunakawa et al 2010). We performed fast Fourier transformation (FFT) to the magnetic field vectors in every 16 s to analyze wave activities in the frequencies from 0.0625 to 16 Hz.…”

Section: Observationsmentioning

confidence: 99%

“…(f) The spacecraft trajectory during 00:00 to 01:00 UT (green line) and magnetic field vectors (magenta arrows) with respect to the Moon. The black contour indicates 0.5-nT magnetic field strength at an altitude of 100 km (Tsunakawa et al 2010). The yellow and gray hemispheres in (f) represent the dayside and nightside of the Moon, respectively.…”

Section: Fundamental and Harmonic Componentsmentioning

confidence: 99%

“…Since the dynamic range of LMAG during the analyzed period was fixed in a range of ±64 nT (Tsunakawa et al 2010), effects of different offsets and linearities between ranges did not affect the output. The linearity of the sensor in a range of ±64 nT was confirmed to be better than 0.2% by the ground calibration (Shimizu et al 2008).…”

Section: Possible Causes Of Harmonicsmentioning

confidence: 99%

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Harmonics of whistler-mode waves near the Moon

Tsugawa

Katoh

Terada

et al. 2015

Earth, Planets and Space

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Harmonic spectral features of electromagnetic waves in the frequencies of several Hz around the Moon have been identified by Kaguya. The waves have steepened waveforms peculiarly in the compressional component. The fundamental waves have almost the same properties as narrowband whistler-mode waves with the frequencies near 1 Hz, which have been observed around the Moon. The waves are observed around the terminator region in the solar wind near the lunar magnetic anomalies at the altitudes under 120 km. We suggest that the harmonic spectra are a result of the nonlinear steepening of narrowband whistler-mode waves. Although the narrowband whistler-mode waves have been observed in the upstream region of many planetary bow shocks, such harmonics have rarely been observed there. Since the harmonics are more frequently observed at lower altitudes of the Moon, they are possibly caused by lunar intrinsic environments including lunar dusts and local structures of lunar magnetic anomalies.

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Section: Observationsmentioning

confidence: 99%

Section: Fundamental and Harmonic Componentsmentioning

confidence: 99%

Section: Possible Causes Of Harmonicsmentioning

confidence: 99%

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Harmonics of whistler-mode waves near the Moon

Tsugawa

Katoh

Terada

et al. 2015

Earth, Planets and Space

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“…The magnetic field data used in this study were obtained by the lunar Lagnetometer (LMAG) of the magnetic field and plasma experiment (MAP) on board Kaguya (Shimizu et al 2008;Takahashi et al 2009;Tsunakawa et al 2010) on its orbit encircling the moon at an altitude of 100 km during the period from 1 January 2008 to 30 September 2008. The period of the orbital motion was about 118 min at that altitude.…”

Section: Instrumentationmentioning

confidence: 99%

“…The reflected protons injected into the solar *Correspondence: nakagawa@tohtech.ac.jp 1 Tohoku Institute of Technology, 35-1 Yagiyama Kasumi-cho, Taihaku-ku, 982-8577, Sendai, Japan Full list of author information is available at the end of the article wind flow generate a variety of wave activity around the moon. Large amplitude, nearly monochromatic ultra-lowfrequency (ULF) waves of 0.01 Hz (Nakagawa et al 2012;Tsunakawa et al 2010) and non-monochromatic whistler waves within the extremely low-frequency (ELF) range from 0.03 to 10 Hz (Nakagawa et al 2011;Tsugawa et al 2012) were most commonly observed around the moon. Significant monochromatic whistler waves were also seen, although they were less common (Nakagawa et al 2003;Tsugawa et al 2011).…”

Section: Introductionmentioning

confidence: 99%

ELF magnetic fluctuations detected by Kaguya in deepest lunar wake associated with type-II protons

et al. 2015

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Magnetic fluctuations in the extremely low-frequency (ELF) range from 0.1 to 10 Hz were found by the Lunar Magnetometer (LMAG) of the magnetic field and plasma experiment (MAP) on board the spacecraft Kaguya in the deepest wake behind the moon, where the magnetic field is usually quiet. The fluctuations were compressional and non-monochromatic, showing no preferred polarization. They were often accompanied by "type-II entry" solar wind protons that were reflected by the dayside lunar surface or crustal magnetic field, gyrated around the solar wind magnetic field, then entered the deepest wake. The ELF waves persisted for 30 s to several minutes. The duration was often shorter than that of the type-II protons. Most of the waves were detected on the magnetic field lines disconnected from the lunar surface, along which the solar wind electrons were injected into the wake. Since a large cross-field velocity difference is expected between the type-II protons and the solar wind electrons injected along the magnetic field, some cross-field current-driven instability such as the lower hybrid two-stream instability is expected to be responsible for the generation of the waves.

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Group‐standing of whistler mode waves near the Moon

et al. 2014

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Narrowband whistler mode waves with frequencies near 1 Hz have been observed near the Moon.We reveal that the narrowband spectra, the frequency concentration near 1 Hz, and the relations between the wave vector, magnetic field vector, and sunward directions can be explained by a condition in which the group velocity vector is almost canceled by the solar wind velocity vector in the spacecraft frame. Hereafter, we refer to this condition as the group-standing condition. The spectral density is modified and has a peak at the frequency satisfying the group-standing condition because of the difference of the frequency width between the solar wind plasma frame and the spacecraft frame. In addition, if the waves were decelerated to be group-standing, the conservation of the energy flux results in the intensification of the wave amplitude at that frequency. We also derive the analytical expression of the amount of the modifications, which depend on the group velocity. These effects can explain the narrowband spectra near 1 Hz and support the relations between the wave vector, magnetic field vector, and sunward directions. The estimated frequency which satisfies the group-standing condition is in good agreement with the observed frequency within error bars of the estimation. Considering the group-standing condition, we suggest that the narrowband waves observed in the spacecraft frame are originated from oblique whistler mode waves in the frequencies near the lower hybrid frequency, which are possibly generated by reflected ions from the lunar magnetic anomalies.

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Lunar Magnetic Field Observation and Initial Global Mapping of Lunar Magnetic Anomalies by MAP-LMAG Onboard SELENE (Kaguya)

Cited by 108 publications

References 51 publications

Harmonics of whistler-mode waves near the Moon

Harmonics of whistler-mode waves near the Moon

ELF magnetic fluctuations detected by Kaguya in deepest lunar wake associated with type-II protons

Group‐standing of whistler mode waves near the Moon

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