Supernova Propagation And Cloud Enrichment: A new model for the origin of ${}^{60}$Fe in the early solar system

The radioactive isotope ${}^{60}$Fe ($T_{1\mathrm{/}2}=1.5$ Myr) was present in the early solar system. It is unlikely that it was injected directly into the nascent solar system by a single, nearby supernova. It is proposed instead that it was inherited during the molecular cloud stage from several supernovae belonging to previous episodes of star formation. The expected abundance of ${}^{60}$Fe in star forming regions is estimated taking into account the stochasticity of the star-forming process, and it is showed that many molecular clouds are expected to contain ${}^{60}$Fe (and possibly ${}^{26}$Al [$T_{1/2} = 0.74 $ Myr]) at a level compatible with that of the nascent solar system. Therefore, no special explanation is needed to account for our solar system’s formation.