The Astrophysical Environment of the Solar Birthplace

Abstract

Our Sun, like all stars, formed within a cold molecular cloud. Astronomical observations and theory provide considerable detail into this process. Yet cosmochemical observations of short lived radionuclides in primitive meteorites, in particular 60Fe, provide unequivocal evidence that the early solar system inherited fresh nucleosynthetic material from the core of a hot, massive star, almost certainly ejected in a supernova explosion. I give a short introduction to the fields of star formation and meteoritics and discuss how the reconciliation of their disparate clues to our origin places strong constraints on the environment of the Solar birthplace. Direct injection of supernova ejecta into a protoplanetary disk or a dense molecular core is unlikely since their small sizes require placement unusually close to the massive star. Lower density molecular cloud clumps can capture more ejecta but the radionuclides decay during the slow gravitational collapse. The most likely scenario is on the largest scales via the formation of enriched molecular clouds at the intersection of colliding supernova bubbles in spiral arms.