Modelling the evolution and nucleosynthesis of carbon-enhanced metal-poor stars

TL;DR

This paper uses binary population simulations to study the origins of carbon-enhanced metal-poor stars, highlighting the roles of nitrogen and fluorine as tracers and discussing implications for stellar evolution and initial mass functions.

Contribution

It introduces binary population models that explain CEMP star characteristics and constrains stellar evolution processes at low metallicity.

Findings

Nitrogen and fluorine are effective tracers of CEMP star origins.

The scarcity of nitrogen-rich CEMP stars constrains the initial mass function modifications.

High CEMP fractions suggest more efficient dredge-up in low-metallicity AGB stars.

Abstract

We present the results of binary population simulations of carbon-enhanced metal-poor (CEMP) stars. We show that nitrogen and fluorine are useful tracers of the origin of CEMP stars, and conclude that the observed paucity of very nitrogen-rich stars puts strong constraints on possible modifications of the initial mass function at low metallicity. The large number fraction of CEMP stars may instead require much more efficient dredge-up from low-metallicity asymptotic giant branch stars.