Effects of Carbon-excess dependent Mass Loss and Molecular Opacities on Models of C-star Evolution
(English)Manuscript (Other academic)
We present models of stellar evolution for a 2Msun-star of initial metallicity Z = 0.01 (scaled solar), with focus on the carbon-star phase, the effects of increasing carbon excess on mass loss and molecular opacities. We employ a new, state-of-the-art theoretical mass-loss prescription for dust-driven winds, which takes effects of the carbon excess into account and implement a set of composition-dependent molecular opacities, which incorporates the changes due to the evolution of the carbon excess. This work should be regarded as an exploratory and comparative study. The stellar evolution models were computed using the MESA code-package (http://mesa.sourceforge.net), which includes a new fast and efficient code for stellar evolution, but still needs further calibration before quantitative comparisons with observations can be made. We find that the development of the carbon excess is controlling much of the carbon-star evolution. A very pronounced superwind is forming and the termination of the AGB happens soon after the star becomes carbon rich, in fact, after only 4-5 thermal pulses, which is much less than in existing models.
Astronomy, Astrophysics and Cosmology
Research subject Astronomy; Physics
IdentifiersURN: urn:nbn:se:uu:diva-99623OAI: oai:DiVA.org:uu-99623DiVA: diva2:208324