Sulphur-bearing carbon chains in IRC+10216

We have updated the chemical model of IRC+10216 developed by Millar, Herbst & Bettens to include recent routes to the formation of sulphuretted hydroc arbons. The routes are based on a quantum chemical study of the S+C2H syste m. In addition, we have altered the parent species for sulphur to reflect n ew observational results. We find that the model calculations give excellen t agreement with the observed column densities, and discuss the significanc e of these reactions to the formation of species as yet unobserved and to d ark interstellar clouds.