Synthesis of complex molecules in dense interstellar clouds via gas-phase chemistry: model update and sensitivity analysis

Abstract

In an effort to update the work of Leung, Herbst & Huebner (1984), aseries of pseudo time-dependent model calculations of the gas-phasechemistry of dense interstellar clouds has been performed. In thesecalculations a revised list of 1958 reactions has been used whichinvolves 206 species and includes a representative sample of complexmolecules. The cloud chemistry has been studied as a function of visualextinction, cloud temperature, and carbon-to-oxygen abundance ratio. Thechanges in the calculated abundances of complex molecules underdifferent physical conditions are emphasized. It is shown that thesespecies can be synthesized under a variety of physical conditions. It isalso shown that complex molecule development does not occur appreciablyin the gas phase in interstellar clouds that are of low density(2×103cm-3) and of low visual extinction(AV = 2).