Evolution and Emission of Cold, Warm and Hot Dust Populations in Diffuse and Molecular Clouds

Abstract

The cyclic evolution of a multimodal interstellar grain population and its chemical, morphological and optical properties are described in terms of dust in molecular and diffuse clouds. The temperatures characteristic of the “large” tenth micron core-mantle particles, which dominate the mass of the dust and the extinction in the visual, are calculated. For typical situations the tenth micron particle temperatures range from 6 K to 15 K in cool molecular clouds and are about 16 K in diffuse clouds. The small (hundredth micron) hump particles and the very small FUV particles (large molecules) are not only warmer but, because of temperature fluctuations, emit radiation at much shorter wavelengths than the tenth micron particles. The model predicts that the relative proportion of small to large particles is larger in diffuse clouds than in molecular clouds so that the mid infrared emission in diffuse clouds is far higher than in molecular clouds. The core-mantle particles are significantly cooler than the graphite-silicate mixture and the emission peak is 70μm higher.KeywordsMolecular CloudDust EmissionInterstellar DustExtinction CurveDust ModelThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.