Chemical modelling of dark clouds in the LMC and SMC

Pseudo-time-dependent model calculations of the chemistry of dark clouds in the Large and Small Magellanic Clouds have been undertaken. Molecular abundances have been determined for a variety of species both at ‘early time’ |$(3.6 \times {10}^{5}\,\text{yr})$| and at steady state |$(\gt{10}^{7}\,\text {yr}).$| Many of the calculated molecular abundances depend, in a complex manner, on the differing elemental abundances of carbon, oxygen and nitrogen in the LMC and SMC. One exception is the abundance of carbon monoxide, which depends linearly on the elemental carbon abundance in regions where the oxygen-to-carbon abundance ratio exceeds unity.