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D.A. Neufeld (JHU), G.J Melnick, J.R. Stauffer, M.L.N. Ashby, E.A. Bergin, S.C. Kleiner, B.M. Patten, R. Plume, V. Tolls, Z. Wang, Y.F. Zhang (CfA), P.F. Goldsmith (Cornell U., NAIC), M. Harwit (Cornell U.), N.R. Erickson, J.E. Howe, R.L. Snell (UMass, Amherst), D.G. Koch (NASA ARC), R. Schieder, G. Winnewisser (U. Koln), G. Chin (NASA GSFC)
We have observed water vapor emission from several protostellar outflow regions with SWAS, including the sources Orion-KL, NGC 2071, NGC 1333 IRAS 4, L1157, RCrA, and L1689N. Observations of the 110-101 water transition toward each of these sources have revealed the presence of broad line emission accompanied by narrow absorption in quiescent foreground gas or -- in the case of Orion-KL, by a narrow emission line component. In each case, the width of the broad emission line component, typically ~20 - 40 \,\rm km \,s-1 (FWHM), suggests an origin in the outflowing gas. From the observed line fluxes, we estimate water abundances ranging from ~10-6 in low mass outflow regions to \rm several \times 10-4 in the Orion-KL region. These values are all significantly larger than the water abundance estimates of ~\rm few \times 10-9 - 10-7 derived from SWAS observations of quiescent regions, implying that the water abundances are enhanced in outflow regions. Such enhancements are indeed expected to result from the effects of shocks in (1) vaporizing icy grain mantles and/or (2) producing water in the gas-phase (by means of neutral-neutral reactions that are negligibly slow at the low temperatures of quiescent clouds but rapid at the elevated temperatures present behind a shock.)
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