Asymptotic Giant Branch Mass-loss Rates and Metal Yields from Scaled Mixing-length and Mass-loss Parameters

Abstract Stars on the asymptotic giant branch (AGB) enrich the interstellar medium with carbon, nitrogen, and dust, which in turn boost cooling and promote future generations of planet and star formation. They are poorly constrained observationally because they remain in this phase briefly and modeling them is also challenging due to complex convective mixing and nucleosynthesis. By incorporating updated opacity tables and instability management techniques into MESA, we compute a new grid of AGB models that densely samples a wide range of initial masses (0.8 ≤ M/M ⊙ ≤ 7) and metal mass fractions (0.0001 ≤ Z ≤ 0.03), and generate updated AGB mass-loss rates and metal yields up to 28 Si for evolution models and cosmological simulations. We develop scaling formulas for varying the convective mixing-length and Blöcker mass-loss parameters, enabling calibration against recent carbon star luminosity observations and hydrodynamic simulation results. Our results are consistent with white dwarf initial–final mass observations, typical AGB mass-loss rates of ∼10 −7 –10 −5 M ⊙ yr −1 , and average luminosities of carbon stars in AGB populations of ∼8200 L ⊙ . We compare yields to previous models, finding similar C, N, O, F, and Ne but significantly enhanced Mg. The surface C/O ratios match other models at high metallicity but tend to be higher at Z ≤ 0.005. Predicted surface metallicities match previous simulation assumptions, but significantly higher AGB outflow rates suggest large systematic uncertainties in the theoretically expected cosmological carbon yield.