Tuesday

The properties of dust in the diffuse interstellar medium (DISM) are still elusive and even the presence of dust in this environment is difficult to account for. The infrared bands show features of both carbonaceous dust species and silicates, enabling us to study the properties of dust. However, most of our current knowledge is limited to a few sightlines toward the Galactic Center.
JWST will provide an important impulse to infrared studies of interstellar dust in the Galactic diffuse ISM. Here we present the modelling of infrared dust features toward a selection of well characterized OB stars in different regions of the Galaxy. We show how the absorption fingerprint of DISM dust along these sightlines can be used to answer several long-standing questions in the cycle of dust in galaxies, namely: what is the composition and lattice structure of DISM silicates? what is the nature of interstellar carbon dust? and what is the location of the missing oxygen in the DISM? Addressing these questions is of fundamental importance, because the DISM is the starting point for star and planet formation, setting the initial
conditions for material that feeds into molecular clouds.