Nan Liu^1,2,3, Roberto Gallino⁴, Sara Bisterzo^4,5, Andrew M. Davis^1,2,6, Michael R. Savina^2,3, and Michael J. Pellin^1,2,3,6

¹Department of the Geophysical Sciences, The University of Chicago, Chicago, IL 60637, USA
²Chicago Center for Cosmochemistry, Chicago, IL 60637, USA
³Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
⁴Dipartimento di Fisica, Università di Torino, Torino I-10125, Italy
⁵INAF-Osservatorio Astrofisico di Torino-Strada Osservatorio 20, Pino Torinese I-10025, Italy
⁶Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637, USA

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.

Reference
Liu N, Gallino R, Bisterzo S, Davis AM, Savina MR and Pellin MJ (in press) The 13C-Pocket Structure in AGB Models: Constraints from Zirconium Isotope Abundances in Single Mainstream SiC Grains. The Astrophysical Journal Letters 788:163.
[doi:10.1088/0004-637X/788/2/163]

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