Constraints on CEMP-no progenitors from nuclear astrophysics

Context. The CEMP-no stars are long-lived small mass stars presenting a very low iron content and overabundances of carbon with no sign or only very weak signs of s- or r-elements. Although the origin of this abundance pattern is still a matter of debate, it was very likely inherited from a previous massive star, which we call the source star. Aims. We rely on a recent classification of CEMP-no stars arguing that some of them are made of a material processed by hydrogen burning that was enriched in products of helium burning during the nuclear life of the source star. We examine the possibility of forming CEMP-no stars with this material. Methods. We study the nucleosynthesis of the CNO cycle and the Ne-Na Mg-Al chains in a hydrogen burning single zone while injecting the helium burning products C-12, O-16, Ne-22, and Mg-26. We investigate the impact of changing density, temperature and the injection rate. The nuclear reaction rates involving the creation and destruction of Al-27 are also examined. Results. N-14, Na-23, Mg-24, and Al-27 are formed when injecting C-12, O-16, Ne-22, and Mg-26 in the hydrogen burning zone. The C-12/C-13 ratio is constant under various conditions in the hydrogen burning zone. The predicted [Al/Fe] ratio varies up to similar to 2 dex depending on the prescription used for the reaction rates involving Al-27. Conclusions. The experiments we carried out support the view that some CEMP-no stars are made of a material processed by hydrogen burning that comes from a massive star experiencing mild to strong rotational mixing. During its burning, this material was likely enriched in helium burning products. No material coming from the carbon-oxygen rich core of the source star should be added to form the daughter star, otherwise the C-12/C-13 ratio would be largely above the observed range of values.