$^{26}$Al production from magnetically induced extramixing in AGB Stars

TL;DR

This paper investigates how magnetic buoyancy-driven extramixing in AGB stars can produce significant amounts of $^{26}$Al, potentially explaining observed presolar grain compositions and early solar system isotope levels.

Contribution

It introduces a magnetic buoyancy model for extramixing in AGB stars and demonstrates its effectiveness in producing $^{26}$Al comparable to other known processes.

Findings

Magnetic buoyancy can produce $^{26}$Al levels matching presolar grain measurements.

Fast-moving magnetic instabilities are nearly as effective as hot bottom burning.

The model suggests AGB stars could have contributed to early solar system $^{26}$Al abundance.

Abstract

We discuss nucleosynthesis results obtained following the recent suggestion that extramixing phenomena in red giants might be driven by magnetic buoyancy. We explore for this model the production of the short-lived radioactive isotope $^{26}$Al and of stable light nuclei, considering both the case of the general buoyancy of flux tubes and that of the intermittent release of magnetized unstable structures. We show that abundant $^{26}$Al can be produced, up to, and above, the highest levels measured in presolar grains. This level would be also sufficient to explain the early solar system $^{26}$Al as coming from a nearby AGB star of low mass. The case of fast-moving instabilities is the most efficient, reaching almost the same effectiveness as hot bottom burning (HBB).