The Effects of a Late Single-Star Contamination of the Solar Nebula on the Early Solar System Radioactivities

Abstract

We re-examine the origin of now-extinct radioactivities, which were alive in the early solar nebula. The Galactic inheritance broadly explains most of the isotopes involved with lifetime T < 5 Myr. Instead, shorter-lived isotopes like 26 Al,41Ca and 135Cs require nucleosynthesis events close in time to the solar formation. Models of final stages of Intermediate-Mass Stars (IMSs) now predict the ubiquitous formation of a 13C-pocket, which always implies large excesses in 107 Pd with respect to 26Al. Even a late contamination by a Massive Star (MS) meets serious problems, because the inhomogeneous addition of Supernova debris yields excesses on stable isotopes that disagree with measurements.