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Abstract: We present a new grid of stellar model calculations for stars on theAsymptotic Giant Branch between 1.0 and 6.0 M sun. Our grid consists of 5chemical mixtures between Z=0.0005 and Z=0.04, with both solar-like and$\alpha$-element enhanced metal ratios. We treat consistently thecarbon-enhancement of the stellar envelopes by using opacity tables withvarying C-O-ratio and by employing theoretical mass loss rates for carbonstars. The low temperature opacities have been calculated specifically for thisproject. For oxygen stars we use an empirical mass loss formalism. The thirddredge-up is naturally obtained by including convective overshooting. Ourmodels reach effective temperatures in agreement with earlier synthetic models,which included approximative carbon-enriched molecular opacities and show goodagreement with empirically determined carbon-star lifetimes. A fraction of themodels could be followed into the post-AGB phase, for which we provide modelsin a mass range supplementing previous post-AGB calculations. Our gridconstitutes the most extensive set of AGB-models, calculated with the latestphysical input data and treating carbon-enhancement due to the third dredge-upmost consistently.



Autor: Achim Weiss, Jason W. Ferguson

Fuente: https://arxiv.org/







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