Proton entry into the near-lunar plasma wake for magnetic field aligned flow

Dhanya, M. B.; Bhardwaj, A.; Futaana, Y.; Fatemi, S.; Holmström, M.; Barabash, S.; Wieser, M.; Wurz, Peter; Alok, A.; Thampi, R. S. (2013). Proton entry into the near-lunar plasma wake for magnetic field aligned flow. Geophysical Research Letters, 40(12), pp. 2913-2917. American Geophysical Union 10.1002/grl.50617

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We report the first observation of protons in the near-lunar (100-200 km from the surface) and deeper (near anti-subsolar point) plasma wake when the interplanetary magnetic field (IMF) and solar wind velocity (vsw) are parallel (aligned flow; angle between IMF and vsw≤10°). More than 98% of the observations during aligned flow condition showed the presence of protons in the wake. These observations are obtained by the Solar Wind Monitor sensor of the Sub-keV Atom Reflecting Analyser experiment on Chandrayaan-1. The observation cannot be explained by the conventional fluid models for aligned flow. Back tracing of the observed protons suggests that their source is the solar wind. The larger gyroradii of the wake protons compared to that of solar wind suggest that they were part of the tail of the solar wind velocity distribution function. Such protons could enter the wake due to their large gyroradii even when the flow is aligned to IMF. However, the wake boundary electric field may also play a role in the entry of the protons into the wake.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences

UniBE Contributor:

Wurz, Peter


500 Science > 520 Astronomy
600 Technology > 620 Engineering
500 Science > 530 Physics




American Geophysical Union




Cléa Serpollier

Date Deposited:

11 Jul 2014 12:19

Last Modified:

18 Sep 2015 14:40

Publisher DOI:





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