摘要：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
12C,
16O,
22Ne, and
26Mg. We
investigate the impact of changing density, temperature and the injection rate. The
nuclear reaction rates involving the creation and destruction of 27Al are also examined.
Results. 14N, 23Na, 24Mg, and 27Al are formed when injecting 12C, 16O, 22Ne, and 26Mg in the hydrogen burning
zone. The 12C/13C ratio is constant under various conditions in the
hydrogen burning zone. The predicted [Al/Fe] ratio varies up to ~ 2 dex depending on the prescription
used for the reaction rates involving 27Al.
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 12C/13C ratio would be largely above the observed range of
values.
