Short-lived nuclides in the early solar system: the stellar connection

Abstract

Fossil evidence for the presence of short-lived nuclides with half-life ranging from 100,000 years to ∼100 million years (Ma) in the early solar system has been found in primitive meteorites. The nuclides with half-life less than a couple of million years ( 41Ca, 26Al, 10Be, 60Fe) must have been produced either shortly before or during the very early evolution of the solar system. Two plausible sources of these nuclides are proposed; a single stellar source (e.g., a TP-AGB star, supernova or a W-R star) or energetic particle production in solar, presolar or stellar environments. The presence of 10Be, which is not a product of stellar nucleosynthesis, argues for an energetic particle production mechanism. However, correlated presence of 41Ca and 26Al with well-defined initial abundances in early solar system objects cannot be explained in the energetic particle production model and it also fails to account for the presence of 60Fe. Recent experimental data demonstrate that the source of 10Be is decoupled from that of 26Al and 41Ca and suggest that both a stellar source as well as energetic particle production contributed to the inventory of the short-lived nuclides in the early solar system. New data for initial abundance of 60Fe in the solar system tend to favor a SN source. The presence of freshly synthesized short-lived nuclides from an evolved star in the early solar system led to the hypothesis of a triggered origin of the solar system. Numerical simulation studies indicate dynamical feasibility of such a process and there are indirect observational evidences for triggered formation of sun-like stars.