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We present stellar evolutionary tracks and nucleosynthetic predictions for a grid of stellar models of low- and intermediate-mass asymptotic giant branch (AGB) stars at $Z=0.001$ ([Fe/H]$=-1.2$). The models cover an initial mass range from 1 M$_{odot}$ to 7 M$_{odot}$. Final surface abundances and stellar yields are calculated for all elements from hydrogen to bismuth as well as isotopes up to the iron group. We present the first study of neutron-capture nucleosynthesis in intermediate-mass AGB models, including a super-AGB model, of [Fe/H] = $-1.2$. We examine in detail a low-mass AGB model of 2 M$_{odot}$ where the $^{13}$C($alpha$,$n$)$^{16}$O reaction is the main source of neutrons. We also examine an intermediate-mass AGB model of 5 M$_{odot}$ where intershell temperatures are high enough to activate the $^{22}$Ne neutron source, which produces high neutron densities up to $sim 10^{14}$ n cm$^{-3}$. Hot bottom burning is activated in models with $M geq 3$ M$_{odot}$. With the 3 M$_{odot}$ model we investigate the effect of varying the extent in mass of the region where protons are mixed from the envelope into the intershell at the deepest extent of each third dredge-up. We compare the results of the low-mass models to three post-AGB stars with a metallicity of [Fe/H] $simeq -1.2$. The composition is a good match to the predicted neutron-capture abundances except for Pb and we confirm that the observed Pb abundances are lower than what is calculated by AGB models.
There is now strong evidence that some stars have been born with He mass fractions as high as $Y approx 0.40$ (e.g., in $omega$ Centauri). However, the advanced evolution, chemical yields, and final fates of He-rich stars are largely unexplored. We i
In this paper we present the evolution of a low mass model (initial mass M=1.5 Msun) with a very low metal content (Z=5x10^{-5}, equivalent to [Fe/H]=-2.44). We find that, at the beginning of the AGB phase, protons are ingested from the envelope in t
We present the dust ejecta of the new stellar models for the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase computed with the COLIBRI code. We use a formalism of dust growth coupled with a stationary wind for both M and C-stars. In the orig
Thermally-Pulsing Asymptotic Giant Branch (TP-AGB) stars are relatively short lived (less than a few Myr), yet their cool effective temperatures, high luminosities, efficient mass-loss and dust production can dramatically effect the chemical enrichme
Common-envelope phases are decisive for the evolution of many binary systems. Of particular interest are cases with asymptotic giant branch (AGB) primary stars, because they are thought to be progenitors of various astrophysical transients. In three-