Potassium abundances in extremely metal poor stars; Implications for nucleosynthesis in the final stages of massive star evolution

Ishigaki, Miho*; Tominaga, Nozomu*; Aoki, Wako*; Wanajo, Shinya*; Takiwaki, Tomoya*; Nakamura, Ko*; Iwamoto, Nobuyuki  ; Nomoto, Kenichi*; Kobayashi, Chiaki*

We present the abundance analysis of Potassium (K) in extremely metal-poor stars based on high-resolution spectra obtained by High-Dispersion Spectrograph on Subaru Telescope. One-dimensional LTE abundances of K as well as other elemental abundances including Na, Mg, Ca, Ti, Cr, and Ni are obtained by a spectral synthesis method. We detect K lines in seven stars with [Fe/H] . We find that [K/Fe] and [K/Ca] ratios of seven stars are enhanced relative to the solar value with scatter smaller than the typical uncertainty. While a significant variation in [Na/Mg] ratios can be seen, the observed small scatter in [K/Fe] and [K/Ca] is in line with a hypothesis that the K in those stars has been produced in the innermost ejecta of core-collapse supernovae whose yields are independent of progenitor masses or metallicities.