New Abundances From Very Old Stars

TL;DR

This study presents a detailed chemical abundance analysis of approximately 25 metal-poor stars, including some of the most ancient stars known, to understand early Galactic nucleosynthesis and the origins of heavy elements.

Contribution

It provides a homogeneous analysis of a significant sample of extremely metal-poor stars, including CEMP stars, with comprehensive element abundances from Li to Ba, enhancing understanding of early stellar populations.

Findings

Identification of stars with [Fe/H] < -4, among the most metal-poor studied to date.

Approximately 20% of stars with [Fe/H] < -3 are CEMP stars.

CEMP stars may originate from binary interactions or early explosive events.

Abstract

Metal-poor stars provide the fossil record of Galactic chemical evolution and the nucleosynthesis processes that took place at the earliest times in the history of our Galaxy. From detailed abundance studies of low mass, extremely metal-poor stars ([Fe/H] < -3), we can trace and help constrain the formation processes which created the first heavy elements in our Galaxy. Here we present the results of a ~25-star homogeneously analysed sample of metal-poor candidates from the Hamburg/ESO survey. We have derived abundances for a large number of elements ranging from Li to Ba, covering production processes from hydrostatic burning to neutron-capture. The sample includes some of the most metal-poor stars ([Fe/H] < -4) studied to date, and also a number of stars enhanced in carbon. The so called CEMP (carbon enhanced metal-poor) stars, these stars make up ~20% of the stars with [Fe/H] < -3, and 80% of the stars with [Fe/H] < -4.5. The progenitors of CEMP stars are still not fully constrained; they could be a result of binary mass transfer or high-mass explosive events in the early universe.