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Neptune's cosmic ray cutoff
Author(s) -
Selesnick R. S.,
Stone E. C.
Publication year - 1991
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/90gl02582
Subject(s) - physics , neptune , cutoff , astrophysics , cosmic ray , magnetosphere , astronomy , magnetic field , planet , quantum mechanics
The Voyager 2 cosmic ray experiment observed the signature of a magnetic cutoff of cosmic ray protons immediately after the closest approach to Neptune. The cutoff signature shows that the simultaneous observation of a trapped particle dropout could not have occurred at high magnetic latitudes, but is likely to be a drift shadow of the planet caused by the large offset of the particle drift shells. The OTD2 dipole model of Neptune's magnetic field predicts a drift shadow at approximately the correct times. In addition, the cutoff signature is similar to that predicted by the OTD2 model, although the model is not accurate throughout the observation period. The similarity is consistent with small estimated corrections to the predicted signature based on the locally observed magnetic field values, indicating that the L shell values derived from the model are approximately valid after the closest approach time.