A runaway wolf-rayet star as the origin of 26Al in the early solar system

Abstract

Establishing the origin of the short-lived radionuclide (SLR) 26Al, which was present in refractory inclusions in primitive meteorites, has profound implications for the astrophysical context of solar system formation. Recent observations that 26Al was homogeneously distributed in the inner solar system prove that this SLR has a stellar origin. In this Letter, we address the issue of the incorporation of hot 26Al-rich stellar ejecta into the cold protosolar nebula. We first show that the 26Al atoms produced by a population of massive stars in an OB association cannot be injected into protostellar cores with enough efficiency. We then show that this SLR likely originated in a Wolf-Rayet star that escaped from its parent cluster and interacted with a neighboring molecular cloud. The explosion of this runaway star as a supernova probably triggered the formation of the solar system. This scenario also accounts for the meteoritic abundance of 41Ca. © 2010. The American Astronomical Society.