The detection of low Eu abundances in extremely metal-poor stars and the origin of r-process elements

We report abundance analyses of three extremely metal-poor stars with [Fe/H] less than or similar to -3 using the Subaru High Dispersion Spectrograph. All are found to have subsolar values of [Eu/Fe]. Comparison with our chemical evolution model of the Galactic halo implies the dominant source of Eu to be the low-mass end of the supernova mass range. Future studies of stars with low Eu abundances will be important to determine the r-process site.