GEOPHYSICAL RESEARCH LETTERS, VOL. 17, NO. 10, PAGES 1701–1704, 1990

Energetic charged particle angular distributions near (r≤2 R_N) and over the pole of Neptune

B. H. Mauk

The Johns Hopkins University Applied Physics Laboratory

M. Kane

The Johns Hopkins University Applied Physics Laboratory

E. P. Keath

The Johns Hopkins University Applied Physics Laboratory

A. F. Cheng

The Johns Hopkins University Applied Physics Laboratory

S. M. Krimigis

The Johns Hopkins University Applied Physics Laboratory

T. P. Armstrong

The University of Kansas

N. F. Ness

Bartol Research Institute, University of Delaware

Abstract

Energetic ion (>28 keV) and electron (>22 keV) pitch angle distributions very close to (r≤2R_N) and over the north planetary pole of Neptune are presented using data from the Low Energy Charged Particle (LECP) and Magnetometer (MAG) Experiments on the Voyager 2 spacecraft. The particle data are temporally structured and spectrally soft; a similarity with Earth-like auroral signatures has previously been noted. However, the pitch angle distributions (showing trapped distributions at high magnetic latitudes) do not support an Earth-like auroral interpretation, and alternative explanations for the temporal dynamics must be sought. Between r∼1.6 and 2.0 R_N and in the vicinity of the magnetic equator, the higher energy ion and electron pitch angle distributions (E≥80 keV) display dramatic ‘‘bite-outs’’ at ∼90°°. This bite-out feature could be caused by interactions with the newly discovered ring 1989N3R. ©The American Geophysical Union 1990

Index Terms: 5719 Planetology: Fluid Planets: Interactions with particles and fields.

Citation: Mauk, B. H., M. Kane, E. P. Keath, A. F. Cheng, S. M. Krimigis, T. P. Armstrong, and N. F. Ness (1990), Energetic charged particle angular distributions near (r≤2 R_N) and over the pole of Neptune, Geophys. Res. Lett., 17(10), 1701–1704.

Copyright 1990 by the American Geophysical Union.