Clues about the first stars from CEMP-no stars

TL;DR

This paper investigates the origins of CEMP-no stars by modeling low-metallicity stellar processes, including rotational mixing, to explain their observed abundance patterns and shed light on the first stars.

Contribution

It introduces new low-metallicity stellar models with rotational mixing to reproduce the diverse abundance ratios observed in CEMP-no stars.

Findings

Models successfully reproduce observed C/N and $^{12}$C/$^{13}$C ratios.

Mixing between burning regions explains the abundance diversity.

Outer stellar layers' ejection accounts for observed chemical signatures.

Abstract

The material used to form the CEMP-no stars presents signatures of material processed by the CNO cycle and by He-burning from a previous stellar generation called the source stars. In order to reproduce the relative abundance ratios like for instance C/N or $^{12}$C/$^{13}$C, some mixing between the two burning regions must have occured in the source stars and only the outer layers of the stars, with modest amount coming from the CO core, must have been expelled either through stellar winds or at the time of the (faint) supernova event. With new models at low metallicity including rotational mixing, we shall discuss how the variety of abundances observed for CEMP-no stars can be reproduced.