Snell, Ronald L.Howe, JEAshby, MLNBergin, EAChin, GErickson, NRGoldsmith, PFHarwit, MKleiner, SCKoch, DGNeufeld, DAPatten, BMPlume, RSchieder, RStauffer, JRTolls, VWang, ZWinnewisser, GZhang, YFMelnick, GJ2024-04-262024-04-262000-01-01https://doi.org/10.1086/312844https://hdl.handle.net/20.500.14394/3294<p>This is the pre-published version harvested from ArXiv. The published version is located at <a href="http://iopscience.iop.org/1538-4357/539/2/L97/">http://iopscience.iop.org/1538-4357/539/2/L97/</a></p>We present a 17-point map of the M17SW cloud core in the 110 → 101 transition of ortho-H2O at 557 GHz obtained with Submillimeter Wave Astronomy Satellite. Water emission was detected in 11 of the 17 observed positions. The line widths of the H2O emission vary between 4 and 9 km s-1 and are similar to other emission lines that arise in the M17SW core. A direct comparison is made between the spatial extent of the H2O emission and the 13CO J = 5 → 4 emission; the good agreement suggests that the H2O emission arises in the same warm, dense gas as the 13CO emission. A spectrum of the H218O line was also obtained at the center position of the cloud core, but no emission was detected. We estimate that the average abundance of ortho-H2O relative to H2 within the M17 dense core is approximately 1 × 10-9, 30 times smaller than the average for the Orion core. Toward the H II region/molecular cloud interface in M17SW the ortho-H2O abundance may be about 5 times larger than in the dense core.ISM : abundancesISM : cloudsISM : moleculesradio lines : ISMAstrophysics and Astronomyarticle