Melnick, G.J. and Tolls, V. and Neufeld, D.A. and Bergin, E.A. and Phillips , T.G. and Wang, S. and Crockett, N.R. and Bell, T.A. and Blake, G.A. and Cabrit, S. and Caux, E. and Ceccarelli, C. and Cernicharo, J. and Comito, C. and Daniel, F. and Dubernet, M.-L. and Emprechtinger, M. and Encrenaz, P. and Falgarone, E. and Gerin, M. and Giesen, T.F. and Goicoechea, J.R. and Goldsmith, P.F. and Herbst, E. and Joblin, C. and Johnstone, D. and Langer, W.D. and Latter, W.D. and Lis, D.C. and Lord, S.D. and Maret, S. and Martin, P.G. and Menten, K.M. and Morris, P. and Muller, H.S.P. and Murphy, J.A. and Ossenkopf, V. and Pagani, L. and Pearson, J.C. and Perault, M. and Plume, R. and Qin, S.-L. and Salez, M. and Schilke, P. and Schlemmer, S. and Stutzki, J. and Trappe, N. and van der Tak, F.F.S. and Vastel, C. and Yorke, H.W. and Yu, S. and Zmuidzinas, J.
Herschel observations of EXtra-Ordinary Sources (HEXOS):
Observations of H2O and its isotopologues towards Orion KL.
Astronomy & Astrophysics, 521 (L27).
We report the detection of more than 48 velocity-resolved ground rotational state transitions of H 16
2 O, H 18
2 O, and H 17
2 O – most for the first time
– in both emission and absorption toward Orion KL using Herschel/HIFI. We show that a simple fit, constrained to match the known emission
and absorption components along the line of sight, is in excellent agreement with the spectral profiles of all the water lines. Using the measured
2 O line fluxes, which are less affected by line opacity than their H 16
2 O counterparts, and an escape probability method, the column densities
of H 18
2 O associated with each emission component are derived. We infer total water abundances of 7.4 × 10−5, 1.0× 10−5, and 1.6 × 10−5 for the
plateau, hot core, and extended warm gas, respectively. In the case of the plateau, this value is consistent with previous measures of the Orion-KL
water abundance as well as those of other molecular outflows. In the case of the hot core and extended warm gas, these values are somewhat higher
than water abundances derived for other quiescent clouds, suggesting that these regions are likely experiencing enhanced water-ice sublimation
from (and reduced freeze-out onto) grain surfaces due to the warmer dust in these sources.
Repository Staff Only(login required)
||Item control page