Chemical evolution in the SMC

Both are metal- and dust-poor, although the SMC is significantly poorer in both. We have recently simulated the chemistry in cold dense regions of the LMC and found that a rich chemistry exists in the gas-phase.

In this paper, we report a companion study of the chemistry of dense regions of the SMC, confining our attention to cold regions of dense clouds with a variety of densities, visual extinctions, and grain temperatures, and a fixed gas-phase temperature. With a gas-to-dust ratio and elemental abundances based on observations and scaling, we found that for molecules like CO and N_2_, which are predominantly formed in the gas phase, their abundances are consistent with the reduced elemental abundances of their constituent elements above 25K; however, for species that are produced fully (e.g., CH_3_OH) or partially on the grain surface (e.g., H_2_CO, NH_3_), the dependence on metallicity can be complex.