Correlated Iron 60, Nickel 62, and Zirconium 96 in Refractory Inclusions and the Origin of the Solar System

We report precise nickel isotopic compositions, measured with high-resolution MC-ICPMS, for calcium-aluminum-rich inclusions (CAIs) considered to be the earliest objects formed in the solar system. The CAIs display correlated anomalies of super(60)Ni and super(62)Ni, possibly coupled with effects on super(96)Zr. This is not predicted from stellar production models unless the super(60)Ni results from the decay of super(60)Fe. The effects show the signature of neutron-burst nucleosynthesis in a massive star. Such a neutron burst is plausibly responsible for the abundance of many of the short-lived radioactivities present in the early solar system; therefore, at least some of the nucleosynthetic heterogeneity previously reported from CAIs, leached carbonaceous chondrites, and presolar grains is likely to have been generated by dust injection from a supernova at a time close to the beginning of the solar system, which is consistent with a trigger for solar nebula collapse, or generated directly by dust injection into the protoplanetary disk.