The distribution of complex organic molecules in Barnard 5

Complex organic molecules (COMs) are prevalent in cold and dense molecular cloud environments and are formed by a combination of gas phase and grain surface chemical reactions. However, open questions remain about the exact formation pathways of many COMs and the desorption mechanisms of molecular ices at low temperatures. The aim of this study was to investigate the distribution of COMs in the area of the so-called methanol hotspot in the Barnard 5 dark cloud (̋S) to better characterize the efficient desorption of COMs in that region, and to set observational constraints on the low-temperature formation of COMs. The IRAM,30m and OSO,20m telescopes were used to make pointed observations toward two positions close to ̋S, i.e., and targeting transitions of and as well as the five-atom COMs and ętForm. Emission from all the targeted COMs is detected toward both and Non-LTE (local thermodynamic equilibrium) radiative transfer models for methanol do not suggest significant differences in the physical conditions of ̋S, and as probed by gas kinetic temperature Tk and H2 volume density n( ). However, the derived values of Tk and n( ) for ̋SS using a new set of collisional rate coefficients differ significantly from previous estimates. Our results indicate that the efficient formation and desorption of COMs is not confined to ̋SS, but is also active at the nearby positions H2 H2 and When compared to COM data from the literature, our data supports a correlation between and as well as the surface formation of by hydrogenation of ętForm.