Sensitivity of the Blue Loops of Intermediate-Mass Stars to Nuclear Reactions

摘要

We investigate the effects of a modification of the ~(14)N(p,γ)~(15)O reaction rate, as suggested by recent evaluations, on the formation and extension of the blue loops encountered during the evolution of the stars in the mass range 5M_(sun) to 12M_(sun). We show that the blue loops of stars in the mass range 5M_(sun) to 8M_(sun), that is the range of super ABG stars, are severely affected by a modification of the important ~(14)N(p,γ)~(15)O reaction rate. We also show that the blue loops can be restored if envelope overshooting is included, which is necessary to explain the observations of the Cepheid stars.