Sulfur chemistry in cometary comae Original Research Article

We have modelled the chemistry which occurs in cometary comae following the sublimation of sulfuretted parent molecules from the nucleus. Our aim is to determine which of the S-bearing molecules observed in comets must be present in the icy nucleus and which may plausibly be produced in the coma. We find that, although chemical reactions are able to generate considerable amounts of some daughter molecules, they cannot produce the observed abundances. In particular, we demonstrate that previously suggested mechanisms for the formation of S2 in the inner coma are unlikely to be important in comets.