Journal article
Lunar precursor effects in the solar wind and terrestrial magnetosphere
Journal of Geophysical Research: Space Physics, Vol.117(A5), A05101
05/2012
DOI: 10.1029/2011JA017289
Abstract
[1] The two ARTEMIS probes observe significant precursor activity upstream from the Moon, when magnetically connected to the dayside lunar surface. The most common signature consists of high levels of whistler wave activity near half of the electron cyclotron frequency. This precursor activity extends to distances of many thousands of km, in both the solar wind and terrestrial magnetosphere. In the magnetosphere, electrons reflect from a combination of magnetic and electrostatic fields above the lunar surface, forming loss cone distributions. In the solar wind they generally form conics, as a result of reflection from an obstacle moving with respect to the plasma frame (just as at a shock). The anisotropy associated with these reflected electrons provides the free energy source for the whistlers, with cyclotron resonance conditions met between the reflected source population and Moonward-propagating waves. These waves can in turn affect incoming plasma, and we observe significant perpendicular electron heating and plasma density depletions in some cases. In the magnetosphere, we also observe broadband electrostatic modes driven by beams of secondary electrons and/or photoelectrons accelerated outward from the surface. We also occasionally see waves near the ion cyclotron frequency in the magnetosphere. These lower frequency waves, which may result from the presence of ions of lunar origin, modulate the whistlers described above, as well as the electrons. Taken together, our observations suggest that the presence of the Moon leads to the formation of an upstream region analogous in many ways to the terrestrial electron foreshock.
Details
- Title: Subtitle
- Lunar precursor effects in the solar wind and terrestrial magnetosphere
- Creators
- J. S Halekas - University of California, BerkeleyA. R Poppe - University of California, BerkeleyW. M Farrell - Ames Research CenterG. T Delory - University of California, BerkeleyV Angelopoulos - University of California, Los AngelesJ. P McFadden - University of California, BerkeleyJ. W Bonnell - University of California, BerkeleyK. H Glassmeier - Technische Universität BraunschweigF Plaschke - University of California, Los AngelesA Roux - Laboratoire de Physique des PlasmasR. E Ergun - University of Colorado Boulder
- Resource Type
- Journal article
- Publication Details
- Journal of Geophysical Research: Space Physics, Vol.117(A5), A05101
- DOI
- 10.1029/2011JA017289
- ISSN
- 0148-0227
- eISSN
- 2156-2202
- Publisher
- Blackwell Publishing Ltd
- Number of pages
- 18
- Language
- English
- Date published
- 05/2012
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199691002771
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