THE CHEMISTRY OF PHOSPHORUS IN HOT MOLECULAR CORES

Hot molecular cores in star-forming regions are known to have gas-phas e chemical compositions determined by the material evaporated from the icy mantles of interstellar grains, followed by subsequent reactions in the gas phase. Current models suggest that the evaporated material is rich in hydrogenated species. In this paper, we consider the chemis try induced in a hot core by the release of phosphine, PH3 from inters tellar grains. We find that PH3 is rapidly destroyed by a series of re actions with atomic hydrogen and is converted, within 10(4) yr, into a tomic P, and PO and PN, with P atoms being the most abundant species. Other P-bearing molecules can be formed in the hot gas, but on time-sc ales that are long compared to those of the hot cores.