Dust formation in the oxygen-rich AGB star IK Tauri

摘要: Aims: We model the synthesis of molecules and dust in inner wind oxygen-rich Mira-type star IK Tau by considering effects periodic shocks induced stellar pulsation on gas following non-equilibrium chemistry shocked layers between 1 R ⋆ 10 . consider a very complete set clusters, combine nucleation phase formation with condensation these clusters into grains. also test impact increasing local density. Our derived molecular abundances properties are compared to most recent observational data. Methods: A semi-analytical formalism based parameterised fluid equations is used describe density, velocity, temperature wind. The described using chemical kinetic network reactions mechanism Brownian formalism. stiff, ordinary, coupled differential solved, abundances, cluster grain size distributions masses derived. Results: drive an active zone where collision destruction CO post-shock triggers C-bearing species such as HCN CS. Most modelled agree well latest values from Herschel data, except for SO 2 NH 3 , whose may not occur Clusters alumina, Al O produced within lead population alumina grains close surface. silicates (Mg SiO 4 ) form at larger radii (r> 3R ), their triggered HSiO H SiO. They efficiently condense reach final distribution ~6 8 major medium peaking ~200 A. This two dust-shell configuration agrees interferometric observations. dust-to-gas mass ratio range 1-6 × -3 observations O-rich stars. Conclusions: results confirm importance chemically shaping AGB stars providing conditions conducive efficient processes. indicate that acceleration will possibly develop radius 4-8 Tau.