Europium Isotopic Abundances in Very Metal Poor Stars

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 the 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( 151 Eu) ≃ fr( 153 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.