Temperature Spectra of Interstellar Dust Grains Heated by Cosmic Rays. III. Mixed-composition Grains

Abstract Icy grains in the interstellar medium and star formation regions consist of a variety materials. Such composite interact differently with cosmic-ray (CR) particles compared to simple single-material grains. We aim calculate spectra energies temperatures mixed-composition undergoing whole-grain heating by CRs. The were assumed mixture carbon olivine, covered ices consisting oxides water. energy temperature for radii 0.05, 0.1, 0.2 μ m impacted CRs calculated eight values column density, relevant molecular clouds star-forming cores. approach takes into account changes ice thickness composition increasing density. These detailed data CR interaction are intended applications astrochemical models. main finding is that more accurate on grain heat capacity other factors prevent frequent 0.1 or larger icy high temperatures.