Composition and Energy Spectra of Heavy Nuclei of Unknown Origin Detected on Skylab

At the orbit of Skylab we observed steeply falling energy spectra of nuclei with $Z>~8$ and 10E40 MeV/amu at intensities much higher than seen outside the magnetosphere. The composition is O: Ne: [Na-Si]: Fe = 100:33:13:({~}2), consistent with that of the solar corona. We suggest that heavy solar-wind ions enter the magnetosphere, are accelerated, and populate the inner radiation belt.