Evolution of massive AGB stars

摘要: We present new computations of the evolution solar metallicity stars in mass range $9 {-} 12$ $M_{\odot}$. This first paper a series focuses on propagation carbon burning flame front and provides detailed analysis structural up to formation neon-oxygen core. Our calculations which do not include overshooting indicate that off-center ignition is restricted small between 9.0 11.3 $M_{\odot}$. The chemical imprints second dredge-ups surface composition are analyzed compared “standard” less massive stars. It results that, aside from being more luminous slightly bluer HR diagram, AGB almost indistinguishable their lower counterparts, as far concerned. During dredge-up, we note however envelope penetrates deeper into He shell than simulations above ~11.0 $M_{\odot}$, depth dredge considerably reduced, marking transition between low also investigate effects nuclear uncertainties associated with $^{12}{\rm{C}}$ + $^{12}{\rm{C}}$ reactions show it has little impact core composition. Finally describe nucleosynthesis structure newly formed