Phosphorus chemistry in the shocked region L1157 B1

Abstract

We study the evolution of phosphorus-bearing species in one-dimensional C-shock models. We find that the abundances of P-bearing species depend sensitively on the elemental abundance of P in the gas phase and on the abundance of N atoms in the pre-shock gas. The observed abundance of PN and the non-detection of PO toward L1157 B1 are reproduced in C-shock models with shock velocity v = 20 km s-1 and pre-shock density n(H2) = 10 4-105 cm-3, if the elemental abundance of P in the gas phase is 10-9 and the N-atom abundance is n(N)/nH 10 -5 in the pre-shock gas. We also find that P-chemistry is sensitive to O- and N-chemistry because N atoms are destroyed mainly by OH and NO. We identify the reactions of O-bearing and N-bearing species that significantly affect P-chemistry. © 2012. The American Astronomical Society. All rights reserved..