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Low- and intermediate-mass stars go through a period of intense mass-loss atthe end of their lives in a phase known as the asymptotic giant branch (AGB).During the AGB a significant fraction of their initial mass is expelled in astellar wind. This process controls the final stages of their evolution andcontributes to the chemical evolution of galaxies. However, the wind-drivingmechanism of AGB stars is not yet well understood, especially so foroxygen-rich sources. Characterizing both the present-day mass-loss and windstructure and the evolution of the mass-loss rate of such stars is paramount toadvancing our understanding of this processes. We modelled the dust envelope ofW Hya using an advanced radiative transfer code. The dust model was analysed inthe light of a previously calculated gas-phase wind model and compared tomeasurements available in the literature, such as infrared spectra, infraredimages, and optical scattered light fractions. We find that the dust spectrumof W Hya can partly be explained by a gravitationally bound dust shell thatprobably is responsible for most of the amorphous Al$_2$O$_3$ emission. Thecomposition of the large ($\sim$\,0.3\,$\mu$m) grains needed to explain thescattered light cannot be constrained, but probably is dominated by silicates.Silicate emission in the thermal infrared was found to originate from beyond 40AU from the star and we find that they need to have substantial near-infraredopacities to be visible at such large distances. The increase in near-infraredopacity of the dust at these distances roughly coincides with a sudden increasein expansion velocity as deduced from the gas-phase CO lines. Finally, therecent mass loss of W Hya is confirmed to be highly variable and we identify astrong peak in the mass-loss rate that occurred about 3500 years ago and lastedfor a few hundred years.

Dusty wind of W Hya. Multi-wavelength modelling of the present-day and recent mass-loss