Multilayer modeling of porous grain surface chemistry - I. The GRAINOBLE model

摘要: Context. Mantles of iced water mixed with carbon monoxyde, formaldehyde, and methanol are formed during the so-called prestellar core phase. In addition, radicals also thought to be on grain surfaces, react form complex organic molecules later on, warm-up phase protostellar evolution. Aims. We aim study formation mantles abundance methanol, trapped in them. Methods. have developed a macrosopic statistic multilayer model that follows time includes two effects may increase number mantles: i) mantle formation, only surface layer is chemically active not entire bulk; ii) porous structure grains allows trapping reactive particles. The considers network H, O, CO forming neutral species such as water, CO, plus several radicals. ran large grid models impact nature structure. we explored how uncertainty other key parameters influences composition. Results. Our predicts relatively high abundances radicals, especially HCO CH3 O( 10 −9 −10 −7 ). approach enables us follow chemical differentiation within mantle, showing far from being uniform. For example, mostly present outer layers mantles, whereas inner layers. overall composition depends density age well some microscopic parameters, diffusion energy hydrogenation reactions activation energy. Comparison observations constrain value last (0.5–0.65 1500 K, respectively) provide indications physical conditions ices.