Journal or Book Title
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.
Snell, Ronald L.; Howe, JE; Ashby, MLN; Bergin, EA; Chin, G; Erickson, NR; Goldsmith, PF; Harwit, M; Kleiner, SC; Koch, DG; Neufeld, DA; Patten, BM; Plume, R; Schieder, R; Stauffer, JR; Tolls, V; Wang, Z; Winnewisser, G; Zhang, YF; and Melnick, GJ, "The distribution of water emission in M17SW" (2000). ASTROPHYSICAL JOURNAL. 632.