MOLECULAR GAS-PHASE COUNTERPARTS TO SOLID-STATE GRAIN MANTLES FEATURES - IMPLICATION FOR GAS GRAIN CHEMISTRY/

We present ISO SWS (AOT6) observations of the protostellar object RAFG L 7009S. This source is particularly interesting for the characterisat ion of chemistry arising from grain surfaces and mantles, since the so lid state features of many simple molecules such as H2O, CO, CO2, (CO2 )-C-13 and CH4 are detected, together with weaker features not yet una mbiguously identified. Gas phase H2O, CO2, CH4 and CO can also be seen superimposed on the much broader solid state features. We derive an e stimate for the gas phase temperature around 50 K. The gas to solid ra tios of these simple molecules is found to be greater than or equal to 0.2 for H2O, similar to 0.2 for CH4, and an order of magnitude lower for CO2. We discuss the possible implications for interstellar chemist ry in such objects.