Temperature Spectra of Interstellar Dust Grains Heated by Cosmic Rays. II. Dark Cloud Cores

Abstract

Abstract Heating of whole interstellar grains induced by cosmic rays (CRs) is an important desorption mechanism for grain surface molecules in interstellar molecular clouds. This study aims to provide detailed temperature spectra for such CR-induced heating. For this, olivine grains with radii of 0.05, 0.1, and 0.2 μm shielded by interstellar gas with isotropic column densities characteristic of dark cores were considered. The accumulation of an ice mantle of increasing thickness was taken into account. The CR energy spectrum was obtained for these column densities for 32 CR constituents. We calculated the frequencies with which a CR nucleus with known energy hits a grain, depositing a certain amount of energy. As a result, we obtain the energy and temperature spectra for grains affected by CR hits. This allows us to improve the existing approaches to CR-induced whole-grain heating in astrochemical modeling.