THE 13C-pocket structure in AGB models: Constraints from zirconium isotope abundances in single mainstream SiC grains

Abstract

We present postprocess asymptotic giant branch (AGB) nucleosynthesis models with different 13C-pocket internal structures to better explain zirconium isotope measurements in mainstream presolar SiC grains by Nicolussi et al. and Barzyk et al. We show that higher-than-solar 92Zr/ 94Zr ratios can be predicted by adopting a 13C-pocket with a flat 13C profile, instead of the previous decreasing-with-depth 13C profile. The improved agreement between grain data for zirconium isotopes and AGB models provides additional support for a recent proposal of a flat 13C profile based on barium isotopes in mainstream SiC grains by Liu et al. © 2014. The American Astronomical Society. All rights reserved..