Follow-up of metal-poor star candidates discovered by narrow-band survey

speaker: Hiroko Okada

Observational determination of the chemical abundance of metal-poor stars is important for understanding the chemical evolution of the early Universe. However, the metal-poor stars discovered by previous surveys are faint, and it is difficult to measure many elements with high precision. We performed photometric observations using the wide-field CMOS camera (Tomo-e Gozen) on the Kiso Schmidt telescope with narrow-band filters sensitive to stellar metallicity to search for bright metal-poor stars. Very metal-poor star candidates with [Fe/H]<-2 were selected for follow-up medium-resolution spectroscopy with the Nayuta telescope. We have established a method for analysing medium-dispersion spectra using 43 stars with metallicity measurements, and determined the metallicity and α-elemental abundance of ~300 metal-poor star candidates that we had followed up so far. As a result, nine new very metal-poor stars and two low-alpha stars were discovered. In this talk, I present the results of the follow-up and the metal-poor star candidate selection methods.