H2CS in outflows of the massive star-forming core DR21(OH)

Abstract

For the first time, using the Submillimeter Array, H2CS emission was observed to show a typical bipolar outflow morphology toward DR21(OH). The emission consisted of a strong concentration toward a hot molecular core (MM1a) and a symmetrically extended feature aligned roughly in the north-south direction. H2CS is one of the hot core species, and its extended emission is expected to result from the interaction between the outflow of MM1a and the dense ambient gas. We derive H2CS column densities of ∼3 × 1015cm-2 and ∼1 × 1015cm -2 toward MM1a and the centers of the extended emission, respectively. Its fractional abundance, f (H2CS) ∼10-9 relative to the total H2 abundance, is comparable to those in other star-forming regions, suggesting that H2CS may be present in a region closer to the center than previously thought. Our results suggest that the observed H2CS emission arises via direct evaporation or sputtering of the solid H2CS on the grain surface, and H2CS may be one of the major sulfur-bearing species residing in the ice grain mantles in a solid form, at least in the case of DR21(OH). © 2011. The American Astronomical Society. All rights reserved.