Open AccessPeriodicity of 151 days in outer heliospheric anomalous cosmic ray fluxes
Author(s) -
Hill M. E.,
Hamilton D. C.,
Krimigis S. M.
Publication year - 2001
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000ja000380
Subject(s) - cosmic ray , physics , heliosphere , astrophysics , helium , interplanetary spaceflight , astronomy , interplanetary medium , interplanetary magnetic field , flux (metallurgy) , charged particle , proton , solar wind , ion , nuclear physics , plasma , atomic physics , materials science , quantum mechanics , metallurgy
Statistically significant variations have been observed in the differential flux of ∼27‐MeV anomalous cosmic ray (ACR) oxygen, helium, and protons at the Voyager 1 spacecraft during 1998 and 1999 (at a helioradius of ∼73 AU). The quasiperiodic variations are in phase, with oxygen and helium having periods near 151 days, while protons exhibit a period of ∼146 days. The Voyager 1 ACRs vary by ∼30% with respect to the trend, and similar galactic cosmic ray variations, if they exist, must be less than ∼5%, probably much less. No similar, significant periodicities have been detected for these same ACR species at Voyager 2 (at 57 AU) during this period. We report on these and other periodicities in the Voyager Low Energy Charged Particle experiment measurements and address the possible connection between this ∼151‐day ACR periodicity and the previously discovered ∼154‐day periodicities in solar flares, the interplanetary magnetic field, and other phenomena.