Chemical signatures of shocks in hot cores

The characteristic chemistry of hot cores arises from the abrupt evaporatio n of icy mantles when a massive star begins to irradiate the interstellar g as in its vicinity. Such stars are also likely to generate powerful winds w hich may initiate shucks in the same interstellar gas. In this paper, we co nsider whether chemical signatures of the passage of a shock through a hot core can be identified. We find that if hydrogenation occurs on surfaces an d freeze-out of heavy gas-phase atoms and molecules is complete before the hot core is established then no such chemical signature exists. However, if some residual material is present in the gas when the hut core is establis hed then the following molecular abundance ratios are significantly affecte d by the presence of a shock: NS/CS, SO/CS, and HCO/H2CO. This result is mo re evident if injection of ices into the gas occur over a finite period, ra ther than instantaneously. We conclude that these molecular abundance ratio s may be useful tracers of the dynamical history of hot cores, and that fol low-up observational studies are required.