Deuterium enrichment of the interstellar grain mantle

Abstract

We carry out Monte-Carlo simulation to study deuterium enrichment of interstellar grain mantles under various physical conditions. Based on the physical properties, various types of clouds are considered. We find that in diffuse cloud regions, very strong radiation fields persists and hardly a few layers of surface species are formed. In translucent cloud regions with a moderate radiation field, significant number of layers would be produced and surface coverage is mainly dominated by photo-dissociation products such as, C,CH_3,CH_2D,OH and OD. In the intermediate dense cloud regions (having number density of total hydrogen nuclei in all forms ~ 2 x 10^4 cm^-3), water and methanol along with their deuterated derivatives are efficiently formed. For much higher density regions (~ 10^6 cm^-3), water and methanol productions are suppressed but surface coverage of CO,CO_2,O_2,O_3 are dramatically increased. We find a very high degree of fractionation of water and methanol. Observational results support a high fractionation of methanol but surprisingly water fractionation is found to be low. This is in contradiction with our model results indicating alternative routes for de-fractionation of water. Effects of various types of energy barriers are also studied. Moreover, we allow grain mantles to interact with various charged particles (such as H^+, Fe^+,S^+ and C^+) to study the stopping power and projected range of these charged particles on various target ices.

16 pages, 7 figures (Accepted to MNRAS, 2015)

References in corpus (12)

• First detection of triply-deuterated methanol
• The importance of the ortho:para H2 ratio for the deuteration of molecules during pre-protostellar collapse
• Formation of water and methanol in star forming molecular clouds
• Chemical modeling of water deuteration in IRAS16293-2422
• Effects of Initial Condition and Cloud Density on the Composition of the Grain Mantle
• Methyl Acetate and its singly deuterated isotopomers in the interstellar medium
• Effective grain surface area in the formation of molecular hydrogen in interstellar clouds
• Deuterium Enrichment of the Interstellar Medium
• Time evolution of simple molecules during proto-star collapse
• Study of the chemical evolution and spectral signatures of some interstellar precursor molecules of adenine, glycine alanine
• Search for Interstellar Adenine
• Monte Carlo simulation to investigate the formation of molecular hydrogen and its deuterated forms

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