Observational Studies of r- and s-Process Elements for Milky Way Stars

Elements heavier than iron-group are produced by rapid and slow neutron-capture processes (r-process and s-process) in the universe. The site of the processes and history of the enrichment in the Milky Way Galaxy have been studied by spectroscopic observations of stars with different ages and population (Galactic disks, halo etc.). The abundance studies of neutron-capture elements for Milky Way stars, including our long-term observational efforts using the spectroscopic survey telescope LAMOST and the 8.2m Subaru Telescope are reviewed. This article covers the observational results on the abundance distributions of heavy elements (Sr, Ba and Eu), and elemental abundance patterns of r- and s-process enhanced stars.