Description
Theoretical models and laboratory experiments show that CH_3_OH is efficiently formed on cold grain surfaces through the successive hydrogenation of CO, forming HCO and H_2_CO as intermediate species. In cold cores and low UV-field illumination photo-dissociation regions (PDRs) the ices can be released into the gas-phase through nonthermal processes such as photodesorption, which considerably increases their gas-phase abundances. We investigate the dominant formation mechanism of H_2_CO and CH_3_OH in the Horsehead PDR and its associated dense core.
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