The Milky Way halo population studied with LAMOST and Subaru

Abstract

Recent large spectroscopic surveys combined with studies on dynamical motions of stars in the Milky Way halo reveal connections between chemical enrichment and galaxy formation. We have determined elemental abundances based on high resolution spectra obtained with the Subaru Telescope High Dispersion Spectrograph for more than 400 very metal poor stars identified by the LAMOST survey. Kinematics of these stars are analyzed combining Gaia astrometry data. This paper provides a brief overview of this program and reports on the results and problems found in the abundance distributions and correlations between elements (e.g., Ti and Sc abundances higher than predictions of standard chemical evolution models), mass and nucleosynthesis of first stars constrained by detailed elemental abundance ratios of extremely metal poor stars, and subgroups of stars identified by the abundance and kinematics data.