2002/11/13 by C. Sandin, C. Sandín, S. Höfner +1 · 1 citation
Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Atmospheric sciences #Drag #Mechanics #Momentum (technical analysis) #Momentum transfer #Physics #Radiative transfer #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1051/0004-6361:20021643
published as Astron.Astrophys. 398 (2003) 253-266 · 15 pages, 5 figures, accepted by A&A
arxiv created 2002/11/13 · openalex publication_date 2003/01/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
Radiative acceleration of newly-formed dust grains and transfer of momentum from the dust to the gas plays an important role for driving winds of AGB stars. Therefore a detailed description of the interaction of gas and dust is a prerequisite for realistic models of such winds. In this paper we present the method and first results of a three-component time-dependent model of dust-driven AGB star winds. With the model we plan to study the role and effects of the gas-dust interaction on the mass loss and wind formation. The wind model includes separate conservation laws for each of the three components of gas, dust and the radiation field and is developed from an existing model which assumes position coupling between the gas and the dust. As a new feature we introduce a separate equation of motion for the dust component in order to fully separate the dust phase from the gas phase. The transfer of mass, energy and momentum between the phases is treated by interaction terms. We also carry out a detailed study of the physical form and influence of the momentum transfer term (the drag force) and three approximations to it. In the present study we are interested mainly in the effect of the new treatment of the dust velocity on dust-induced instabilities in the wind. As we want to study the consequences of the additional freedom of the dust velocity on the model we calculate winds both with and without the separate dust equation of motion. The wind models are calculated for several sets of stellar parameters. We find that there is a higher threshold in the carbon/oxygen abundance ratio at which winds form in the new model. The winds of the new models, which include drift, differ from the previously stationary winds, and the winds with the lowest mass loss rates no longer form.