2017MNRAS.466.1709T

Dust formation and the resulting mass loss around asymptotic giant branch (AGB) stars with initial metallicity in the range 0 <= Z_ini <= 10^–4 and initial mass 2 <= M_ini/M_☉ <= 5 are explored by hydrodynamical calculations of the dust-driven wind (DDW) along the AGB evolutionary tracks. We employ the MESA code to simulate the evolution of stars, assuming an empirical mass-loss rate in the post-main-sequence phase and considering three types of low-temperature opacity (scaled-solar, CO-enhanced and CNO-enhanced opacity) to elucidate the effect on stellar evolution and the DDW. We find that the treatment of low-temperature opacity strongly affects dust formation and the resulting DDW; in the carbon-rich AGB phase, the maximum {dot}M of M_ini >= 3 M_☉ stars with the CO-enhanced opacity is at least one order of magnitude smaller than that with the CNO-enhanced opacity. A wide range of stellar parameters being covered, the necessary condition for driving efficient DDW with {dot}M ≥10^–6 M_☉ yr^–1 is expressed as effective temperature T_eff <= 3850 K and log (δ_CL/κ_RM) >= 10.43log T_eff - 32.33, with the carbon excess δ_C defined as ε_C - ε_O, the Rosseland mean opacity κ_R in units of cm² g^–1 in the surface layer and the stellar mass (luminosity) M(L) in solar units. The fitting formulae derived for gas and dust mass-loss rates in terms of input stellar parameters could be useful for investigating the dust yield from AGB stars in the early Universe being consistent with stellar evolution calculations.