Project P5: Dust opacity measurements for debris disks

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Dust particles in debris disks have, most likely, a complex composition and structure, which should determine their emissivity at the far-infrared and (sub-)millimeter wavelengths, at which they are primarily observed. A safe interpretation of observational data at these wavelengths thus requires a profound knowledge of various optical material properties and of the optics of such complex particle structures. With this project we aim at determining optical data for (possible) dust constituent materials in the relevant wavelength and temperature range, and at measuring the opacity of complex dust mixtures as benchmark results for optical models. In terms of underlying physics, the first issue will address mainly the influence of temperature and of structural defects on absorption indices of individual materials, while with the second we will investigate the influence of porosity and of strongly absorbing admixtures on the effective absorption cross section. We will closely collaborate with projects P6, P7, and P8 for the choice and production of samples, while measured opacity data of porous and inhomogeneous agglomerates will be compared with the simulations performed in P4, and measured optical constants will be used in those simulations.