Impact of the Small-Scale Spatial Distribution of Dust Particles on the Chemical Evolution of the Diffuse Interstellar Medium

In this work we analyze the effect of gas-dust clumps, possibly formed in the interstellar medium due to instability, described in [10], on the chemical evolution of the diffuse interstellar medium. For this purpose we calculate chemical evolution with common parameters of diffuse interstellar medium (ISM). It is shown that abundances of most observed molecules are higher in a model of the diffuse medium with clumps than in a model with homogeneous dust distribution. In some cases it leads to better agreement of modelling abundances and their relations with observational data. But at the same time, it does not mean that the hypothesis about inhomogenous dust distribution can qualitatively improve the agreement between modelling and observational data on the chemical composition of the diffuse interstellar medium. The best-fit range of values of the physical characteristics of the medium is wider under the assumption that dust can form compact gas-dust clumps and is not uniformly mixed with gas. Results described in this work show that small-scale ( $$ \leqslant {\kern 1pt} 1$$ au) inhomogeneities of the interstellar medium can be important for its chemical evolution.