The s-Process Nucleosynthesis in Extremely Metal-Poor Stars as the Generating Mechanism of Carbon Enhanced Metal-Poor Stars

TL;DR

This paper investigates the role of s-process nucleosynthesis in extremely metal-poor AGB stars as a mechanism for creating carbon-enhanced metal-poor stars, clarifying their chemical origins and the influence of oxygen.

Contribution

It demonstrates that s-process efficiency in EMP AGB stars is governed by oxygen rather than iron, explaining observed abundance patterns in CEMP stars.

Findings

s-process efficiency is controlled by oxygen at low metallicity

abundance ratios of Sr, Ba, Pb to C are explained by binary wind accretion

CEMP-no stars' origins are linked to s-process in EMP AGB stars

Abstract

The origin of carbon-enhanced metal-poor (CEMP) stars plays a key role in characterising the formation and evolution of the first stars and the Galaxy since the extremely-poor (EMP) stars with [Fe/H] \leq -2.5 share the common features of carbon enhancement in their surface chemical compositions. The origin of these stars is not yet established due to the controversy of the origin of CEMP stars without the enhancement of s-process element abundances, i.e., so called CEMP-no stars. In this paper, we elaborate the s-process nucleosynthesis in the EMP AGB stars and explore the origin of CEMP stars. We find that the efficiency of the s-process is controlled by O rather than Fe at [Fe/H] \lesssim -2. We demonstrate that the relative abundances of Sr, Ba, Pb to C are explained in terms of the wind accretion from AGB stars in binary systems.