Origin of short–lived radionuclides

This paper reviews the evidence for short-lived radionuclides in the early Solar System and critically evaluates models for their origin. Radionuclides with half-lives of less than 50 Myr for which firm and consistent evidence has been found are 10Be, 26Al, 41Ca, 53Mn, 60Fe, 107Pd, 129I and 182Hf. The oldest Solar System objects, calcium-aluminium-rich inclusions (CAIs), contained 10Be, 26Al, 41Ca and 53Mn on formation. We discuss whether a spallation or stellar origin for the radionuclides is more likely, and conclude that the initial presence of short-lived radionuclides in CAIs can be most easily explained if these formed by spallation reactions close to the protosun.