Extinction signatures of amorphous carbon grains from the vacuum UV to the far-IR

Abstract

Among the various components of cosmic dust, amorphous carbon grains play a relevant role. Together with other carbon-based materials. they have been invoked to interpret a number of spectral features observed in the interstellar and circumstellar environments. In order to validate, on a more quantitative basis, the reliability of such hypotheses. it is necessary to analyse in detail the optical properties of “analogue” grains produced in the laboratory. In the present paper, we report, for the first time, a complete spectral analysis of the extinction properties measured on various kinds of amorphous carbon grains, from the vacuum UV to the far-IR. These data can be complemented with other experimental results obtained on the same samples by means of different analytical techniques. This approach allows us to propose a self-consistent interpretation about the actual physico-chemical properties of our cosmic dust analogues. The resulting scenario provides a powerful tool to interpret astronomical observations concerning cosmic dust.