Sulfur Chemistry in L1157-B1

Abstract

The main carrier of sulfur in dense clouds, where it is depleted from the gas phase, remains a mystery. Shock waves in young molecular outflows disrupt the ice mantles and allow us to directly probe the material that is ejected into the gas phase. A comprehensive study of sulfur-bearing species toward L1157-B1, a shocked region along a protostellar outflow, has been carried out as part of the IRAM-30 m large program ASAI. The data set contains over 100 lines of CCS, H 2 CS, OCS, SO, SO 2 , and isotopologues. The results of these observations are presented, complementing previous studies of sulfur-bearing species in the region. The column densities and fractional abundances of these species are measured and together these species account for 10% of the cosmic sulfur abundance in the region. The gas properties derived from the observations are also presented, demonstrating that sulfur bearing species trace a wide range of different gas conditions in the region.