The Role of Massive Agb Stars in the Early Solar System Composition

TL;DR

This paper proposes that a massive AGB star could be the primary source of short-lived radionuclides in the early solar system, matching observed abundances without overproducing certain isotopes.

Contribution

It introduces a detailed model of a 6.5 solar mass AGB star that explains early solar system radionuclide abundances, addressing previous skepticism about AGB stars' role.

Findings

Model matches 26Al, 41Ca, 60Fe, 107Pd abundances

Pollution does not overproduce 53Mn

AGB star contribution is consistent with isotopic ratios

Abstract

We demonstrate that a massive asymptotic giant branch (AGB) star is a good candidate as the main source of short-lived radionuclides in the early solar system. Recent identification of massive (4-8 solar masses) AGB stars in the Galaxy, which are both lithium- and rubidium-rich, demonstrates that these stars experience proton captures at the base of the convective envelope (hot bottom burning), together with high-neutron density nucleosynthesis with 22Ne as a neutron source in the He shell and efficient dredge-up of the processed material. A model of a 6.5 solar masses star of solar metallicity can simultaneously match the abundances of 26Al, 41Ca, 60Fe, and 107Pd inferred to have been present in the solar nebula by using a dilution factor of 1 part of AGB material per 300 parts of original solar nebula material, and taking into account a time interval between injection of the short-lived nuclides and consolidation of the first meteorites equal to 0.53 Myr. Such a polluting source does not overproduce 53Mn, as supernova models do, and only marginally affects isotopic ratios of stable elements. It is usually argued that it is unlikely that the short-lived radionuclides in the early solar system came from an AGB star because these stars are rarely found in star forming regions, however, we think that further interdisciplinary studies are needed to address the fundamental problem of the birth of our solar system.