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|Title:||Correlated Strontium and Barium Isotopic Compositions of Acid-cleaned Single Mainstream Silicon Carbides from Murchison||Authors:||Liu, Nan
Savina, Michael R.
Davis, Andrew M.
Pellin, Michael J.
|Issue Date:||2015||Journal:||THE ASTROPHYSICAL JOURNAL||Number:||803||Issue:||1||First Page:||12||Abstract:||We present strontium, barium, carbon, and silicon isotopic compositions of 61 acid-cleaned presolar SiC grains from Murchison. Comparison with previous data shows that acid washing is highly effective in removing both strontium and barium contamination. For the first time, by using correlated 88Sr/86Sr and 138Ba/136Ba ratios in mainstream SiC grains, we are able to resolve the effect of 13C concentration from that of 13C-pocket mass on s-process nucleosynthesis, which points toward the existence of large 13C pockets with low 13C concentrations in asymptotic giant branch stars. The presence of such large 13C pockets with a variety of relatively low 13C concentrations seems to require multiple mixing processes in parent asymptotic giant branch stars of mainstream SiC grains||Acknowledgments:||We thank the anonymous referee for a careful and constructive reading of the manuscript. We thank Prof. Ernst Zinner for his help with the NanoSIMS measurement. We also thank Drs. Oscar Straniero and Luciano Piersanti for many enlightening discussions on stellar modeling. The CHARISMA instrument at Argonne National Laboratory is supported in part by the U.S. Department of Energy, Office of Science, Materials Sciences and Engineering Division. N.L. acknowledges the NASA Earth and Space Sciences Fellowship program (NNX11AN63H) for support. N.L. and A.M.D. acknowledge the NASA Cosmochemistry program (NNX09AG39G) for support. M.R.S. acknowledges support from the NASA Cosmochemistry program (NNH08AI81I). S.B. acknowledges financial support from the Joint Institute for Nuclear Astrophysics (JINA, University of Notre Dame, USA) and from Karlsruhe Institute of Technology (KIT, Karlsruhe, Germany). SC acknowledges the Italian grants RBFR08549F-002 (FIRB 2008 program) and PRIN-MIUR 2012 “Nucleosynthesis in AGB stars: An integrated approach” project (20128PCN59) for support. Part of the Torino model numerical calculations have been sustained by the B 2 FH Association ( http://b2fh.org/ ).||URI:||http://hdl.handle.net/20.500.12386/23274||URL:||https://iopscience.iop.org/article/10.1088/0004-637X/803/1/12||ISSN:||0004-637X||DOI:||10.1088/0004-637X/803/1/12||Bibcode ADS:||2015ApJ...803...12L||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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