http://arxiv.org/abs/2301.01180
Stellar winds of cool and pulsating asymptotic giant branch (AGB) stars enrich the interstellar medium with large amounts of processed elements and various types of dust. We present a first study on the influence of gas-to-dust drift on ab initio simulations of stellar winds of M-type stars driven by radiation pressure on forsterite particles. Our study is based on our radiation hydrodynamic model code T-800 that includes frequency-dependent radiative transfer, dust extinction based on Mie scattering, grain growth and ablation, gas-to-dust drift using one mean grain size, a piston that simulates stellar pulsations, and an accurate high spatial resolution numerical scheme. To enable this study, we calculated new gas opacities based on the \textsc{exomol} database, and we extended the model code to handle the formation of minerals that may form in M-type stars. We discern effects of drift by comparing drift models to our new and extant non-drift models. Compared to our recent results of C-rich stellar winds, our two new drift models based on an oxygen-rich chemistry show drift velocities that are higher by about a factor ten, that is 310-360 $\text{km}\,\text{s}^{-1}$. Our new drift model mass-loss rates are 8-20 times lower than our own non-drift models, but compared to extant models that use the same stellar parameters, our mass-loss rates are 10-420 times lower. Meanwhile, a comparison of other properties such as the expansion velocity and grain size show similar values. Our results show that the inclusion of gas-to-drift is of fundamental importance in stellar wind models driven by transparent grains such as forsterite. Assuming that the drift velocity is insignificant, properties such as the mass-loss rate may be off from more realistic values by a factor one hundred and more.
C. Sandin, L. Mattsson, K. Chubb, et. al.
Wed, 4 Jan 23
30/43
Comments: 13 pages, 6 figures, submitted
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