Influence of Ambient Conditions and Dust Parameters on the Thermal Desorption Rate of Ice Mantle

In this work, we present the calculations of dust temperature and thermal desorption rates in cold molecular clouds with taking into account the stochasting heating of dust grains by ultraviolet (UV) radiation field and cosmic rays (CRs) including secondary electrons. The calculations were carried out for dust grains with radius of their core within the range from 0.005 to 0.25 ?m. Silicate and graphite grains covered by ice mantle (H2O) with thickness corresponding to the volume proportions Sil/Gra : H2O = 3:1 and 1:1 were considered. For each dust composition, the closest physical properties (heat capacity, absorption cross sections, stopping power) were used. Thermal desorption rates vary up to several orders depending on dust size and up to factor of 2 depending on the position in a cloud and dust core material. The obtained thermal desorption rates differ from the estimates available in literature up to 2 orders depending on dust size and outer conditions.