Interstellar extinction: a parametrical study by using laboratory data

Summary

In this paper we present a comparative study between laboratory data, astronomical observations and theoretical models in order to provide a contribution to the characterization ofcosmic-dust properties. In particular, we propose a parametrization of the amorphous-carbon extinction curve. The laboratory extinction measurements, performed in the extreme ultraviolet spectral region, are compared to the UV interstellar extinction curves provided by the IUE satellite. The aim of our work was to define a model that could describe both observational and laboratory data. To this purpose we referred to the model developed by Fitzpatrick and Massa. The second step of the study was the determination of extinction coefficients, for two different size distributions of amorphous-carbon grains, by means of the optical constants,n andk, derived by Rouleau and Martin.