Europium Isotopic Abundances in Very Metal-poor Stars
نویسندگان
چکیده
Europium isotopic abundance fractions are reported for the very metal-poor, neutron-capture-rich giant stars CS 22892-052, HD 115444, and BD +17◦3248. The abundance fractions, derived from analysis of several strong Eu II lines appearing in high-resolution spectra of these stars, are in excellent agreement with each other and with their values in the Solar System: fr(Eu)≃ fr(Eu) ≃ 0.5. Detailed abundance studies of very metal-poor stars have previously shown that the total elemental abundances of stable atoms with atomic numbers z ≥ 56 typically match very closely those of a scaled solar-system r-process abundance distribution. The present results for the first time extend this agreement to the isotopic level. Subject headings: stars: abundances — stars: Population II — Galaxy: halo — Galaxy: abundances — nuclear reactions, nucleosynthesis, abundances
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