Ca. Prombo et al., S-PROCESS BA ISOTOPIC COMPOSITIONS IN PRESOLAR SIC FROM THE MURCHISONMETEORITE, The Astrophysical journal, 410(1), 1993, pp. 393-399
We have measured, by thermal ionization mass spectrometry, the isotopi
c composition of Ba in interstellar SiC-enriched samples (the KJ serie
s) prepared from the Murchison meteorite. Ba in these samples is stron
gly enriched in components plausibly understood as s-process nucleosyn
thetic products. Inferred s-process compositions are different from th
e average s-process contribution to solar system materials in the sens
e of indicating lower effective neutron exposure. There are variations
in s-process compositions which correlate with grain size, indicating
lower neutron exposure for the larger grains. The inferred s-process
compositions differ significantly from previous theoretical prediction
s, indicating the need for revision of relevant neutron capture cross
sections and providing a target for more detailed modeling of s-proces
s nucleosynthesis in specific stellar environments.