On the chemical composition of the evolved very bright metal‐poor star HD 1936

Abstract

We present chemical abundances of the very bright metal‐poor star HD 1936 based on high‐resolution and high SNR spectra from AUKR. We obtain the abundances of 29 atomic species with atomic numbers between 3 and 63. In this context, the derived lithium abundance of 1.01 is consistent with the thin Li plateau observed in lower red giant branch stars. The star is a carbon‐normal with a ratio of −0.31, just like other low‐luminosity red giants on the thin Li plateau. We find the ratios of [Eu/Fe] = 0.43 and [Ba/Eu] = −0.64, indicating very little s‐process contamination. These ratios allow us to classify the star as a moderately r‐process‐enhanced (r‐I) metal‐poor star for the first time. It is worth mentioning that the star has a metallicity of −1.74, a [Cu/Fe] of −0.74, a [Zn/Fe] of 0.04, and a [Mg/C] of 0.69. The results suggest that it may be a second‐generation star formed in a multi‐enriched environment, rather than being a descendant of very massive first‐generation stars. A last point worth mentioning is the possibility that HD 1936 may host a sub‐stellar component with a mass of . Although our study does not confirm or deny this, we briefly discuss the possibility of the star hosting a planet.