INJECTION OF SHORT-LIVED ISOTOPES INTO THE PRESOLAR CLOUD

The evidence for short-lived isotopes such as Al-26 and Ca-41 in meteo rites requires their production either by irradiation in the solar neb ula or by nucleosynthesis in a supernova or other evolved star. In the latter case, nucleosynthesis must be followed promptly by injection o f the isotopes into the presolar cloud, a feat presumably accomplished by the same stellar outflow that transported the isotopes to the pres olar cloud and possibly triggered its collapse. If their nucleosynthes is occurs deep within an unmixed star, the short-lived isotopes may la g far behind the leading edge of the stellar outflow, perhaps preventi ng their injection. However, we show that lagging isotopes can be inje cted into a collapsing protostar with an efficiency similar to that of material in the leading edge of the outflow, because fast-moving isot opes initially far behind (approximately a few parsecs) the leading ed ge impact and enter the cloud while the injection process is still und erway. Isotope injection proceeds through Rayleigh-Taylor-like clumps in the shack-compressed target cloud.