COLLATERAL EFFECTS ON SOLAR NEBULA OXYGEN ISOTOPES DUE TO INJECTION OF 26Al BY A NEARBY SUPERNOVA

Injection of material from a core-collapse supernova into the solar system's already-formed disk is one proposed mechanism for producing the short-lived radionuclides, such as Al-26 and Ca-41, inferred from isotopic studies of meteorites to have existed in the solar nebula. This hypothesis has recently been challenged on the basis that the injection of enough supernova material to match the meteoritic abundances of Al-26 and Ca-41 would produce large, measurable, and unobserved collateral effects on oxygen isotopes. Here we calculate again the shifts in oxygen isotopes due to the injection of supernova material in the solar nebula, using a variety of nucleosynthetic conditions of our own progenitor explosions. Unlike previous studies of this type, we also consider the effect of non-homogeneity in abundance distribution of the nucleosynthesis products after the explosion. We calculate the shifts in oxygen isotopes due to the injection of sufficient supernova material to produce the meteoritic abundances of Al-26 and Ca-41, and analyze the predicted shifts in detail for compatibility with meteoritic data. We find that the range in possible isotopic shifts is considerable and sensitive to parameters such as progenitor mass and anisotropy of the explosion; however, a small number of compatible scenarios do exist. Because of the wide range of outcomes and the sensitivity of isotopic yields to assumed conditions, it is difficult to constrain the supernova that may have led to the injection of Al-26 in the solar nebula. Conversely, we argue that the existence of viable counterexamples demonstrates that it is premature to use oxygen isotopes to rule out the injection of Al-26 and Ca-41 into the solar nebula protoplanetary disk by a nearby supernova.