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Recent evidence from the Pierre Auger Observatory suggests a transition, at 5EeV-10EeV in the composition of Ultra High Energy Cosmic Rays (UHECRs), fromprotons to heavier nuclei such as iron. I consider here the implications of theheavier composition on the sources of UHECRs. The smaller magnetic rigidityimplies that nuclei UHECRs are: (i) More easily accelerated (ii) Local, as theycan diffuse only a few Mpc from their sources before disintegrating (iii)Isotropic, because large deflections in the extra galactic and the galacticmagnetic fields erase the directional information. Uncertainties in thestrength and structure of the the extra galactic magnetic field (EGMF) makes itdifficult to estimate the overall effects. However, with typical reasonableparameters of a few nG and a coherence distance of a Mpc the distance a nucleiUHECR above the GZK energy traverses before photodisintegrating is only a fewMpc. In spite of the significantly weaker limits on the luminosity, Cen A isthe only currently active potential source of nuclei UHECRs within thisdistance. The large deflections erases the directional anisotropy expected froma single source. If indeed the composition of above-GZK-UHECRs is iron and ifthe EGMF is not too small then Cen A is the dominant source of observed nucleiUHECRs above the GZK limit.

A New Limit on the Distances of Nuclei UHECRs Sources