Cosmic Ray and Solar Particle Investigations Over the South Polar Regions of the Sun

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Science  19 May 1995:
Vol. 268, Issue 5213, pp. 1019-1023
DOI: 10.1126/science.268.5213.1019


Observations of galactic cosmic radiation and anomalous component nuclei with charged particle sensors on the Ulysses spacecraft showed that heliospheric magnetic field structure over the south solar pole does not permit substantially more direct access to the local interstellar cosmic ray spectrum than is possible in the equatorial zone. Fluxes of galactic cosmic rays and the anomalous component increased as a result of latitude gradients by less than 50% from the equator to -80°. Thus, the modulated cosmic ray nucleon, electron, and anomalous component fluxes are nearly spherically symmetric in the inner solar system. The cosmic rays and the anomalous nuclear component underwent a continuous, -26 day recurrent modulation to -80.2°, whereas all recurring magnetic field compressions and recurring streams in the solar wind disappeared above ∼55°S latitude.