TY - JOUR
T1 - Non-monochromatic whistler waves detected by Kaguya on the dayside surface of the moon
AU - Nakagawa, Tomoko
AU - Takahashi, Futoshi
AU - Tsunakawa, Hideo
AU - Shibuya, Hidetoshi
AU - Shimizu, Hisayoshi
AU - Matsushima, Masaki
N1 - Funding Information:
Acknowledgments. The authors are grateful to S. Machida, Y. Kasahara, K. Tsubouchi, M. Nishino, and S. Matsukiyo for valuable comments and discussion. The authors are thankful to Y. Saito for the E-t diagram in Fig. 7 and Y. Kasahara for the electron density measured by LRS/WFC. This work was supported by JSPS Grant-in-Aid for Scientific Research project 21540461.
Publisher Copyright:
© 2011 The Society of Geomagnetism and Earth, Planetary and Space Sciences, The Seismological Society of Japan.
PY - 2011
Y1 - 2011
N2 - Non-monochromatic fluctuations of the magnetic field over the frequency range of 0.03-10 Hz were detected by Kaguya at an altitude of 100 km above the lunar surface. The fluctuations were almost always observed on the solar side of the moon, irrespective of the local lunar crustal field. They were also detected just nightside of the terminator (SZA < 123°), but were absent around the center of the wake. The level of the fluctuation enhanced over the wide range from 0.03 to 10 Hz, with no clear peak frequency. The fluctuations had the compressional component, and the polarization was not clear. The fluctuations were supposed to be whistler waves generated by the protons reflected by the lunar surface. The reflected protons are scattered in various directions, resulting a wide range of distribution of the velocity component parallel to the magnetic field. It may account for the wide range of frequency as observed, through cyclotron resonance of the wave with the reflected ions, in which the resonant frequency depends on the velocity component parallel to the magnetic field. However, there is also the possibility that the waves were generated by some nonresonant process.
AB - Non-monochromatic fluctuations of the magnetic field over the frequency range of 0.03-10 Hz were detected by Kaguya at an altitude of 100 km above the lunar surface. The fluctuations were almost always observed on the solar side of the moon, irrespective of the local lunar crustal field. They were also detected just nightside of the terminator (SZA < 123°), but were absent around the center of the wake. The level of the fluctuation enhanced over the wide range from 0.03 to 10 Hz, with no clear peak frequency. The fluctuations had the compressional component, and the polarization was not clear. The fluctuations were supposed to be whistler waves generated by the protons reflected by the lunar surface. The reflected protons are scattered in various directions, resulting a wide range of distribution of the velocity component parallel to the magnetic field. It may account for the wide range of frequency as observed, through cyclotron resonance of the wave with the reflected ions, in which the resonant frequency depends on the velocity component parallel to the magnetic field. However, there is also the possibility that the waves were generated by some nonresonant process.
UR - http://www.scopus.com/inward/record.url?scp=84859380655&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84859380655&partnerID=8YFLogxK
U2 - 10.5047/eps.2010.01.005
DO - 10.5047/eps.2010.01.005
M3 - Article
AN - SCOPUS:84859380655
SN - 1343-8832
VL - 63
SP - 37
EP - 46
JO - earth, planets and space
JF - earth, planets and space
IS - 1
ER -