S22A0068

We propose to obtain high-resolution, high-quality near infrared spectra of very metal-poor ([Fe/H]<−2) stars with IRD for accurate and precise measurements of Si and Sr abundances. These are key elements for constraining early nucleosynthesis and chemical evolution in the Galaxy, but previous studies rely on only a few spectral lines in the optical range. Our recent study based on the previous run (S20A-101) established observation and abundance analysis procedures and obtained reliable Si and Sr abundances for several very metal-poor stars. This is extended to a large sample of very metal-poor stars by this program. The goal is to determine the abundances with precision as good as 0.1 dex, based on a much larger number of spectral lines than previous studies, for about 40 bright metal-poor stars. This will enable us to determine abundance trends and scatter at low metallicity for Si and Sr, which will become a standard data set that will be compared with chemical-evolution models.

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