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    Herschel observations of EXtra-Ordinary Sources (HEXOS): Observations of H2O and its isotopologues towards Orion KL


    Melnick, G.J., Tolls, V., Neufeld, D.A., Bergin, E.A., Phillips , T.G., Wang, S., Crockett, N.R., Bell, T.A., Blake, G.A., Cabrit, S., Caux, E., Ceccarelli, C., Cernicharo, J., Comito, C., Daniel, F., Dubernet, M.-L., Emprechtinger, M., Encrenaz, P., Falgarone, E., Gerin, M., Giesen, T.F., Goicoechea, J.R., Goldsmith, P.F., Herbst, E., Joblin, C., Johnstone, D., Langer, W.D., Latter, W.D., Lis, D.C., Lord, S.D., Maret, S., Martin, P.G., Menten, K.M., Morris, P., Muller, H.S.P., Murphy, J.Anthony, Ossenkopf, V., Pagani, L., Pearson, J.C., Perault, M., Plume, R., Qin, S.-L., Salez, M., Schilke, P., Schlemmer, S., Stutzki, J., Trappe, Neil, van der Tak, F.F.S., Vastel, C., Yorke, H.W., Yu, S. and Zmuidzinas, J. (2010) Herschel observations of EXtra-Ordinary Sources (HEXOS): Observations of H2O and its isotopologues towards Orion KL. Astronomy & Astrophysics, 521 (L27). pp. 1-5. ISSN 0004-6361

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    Abstract

    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 H 18 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.
    Item Type: Article
    Additional Information: © ESO 2010 The original publication is available at DOI: 10.1051/0004-6361/201015085
    Keywords: ISM; abundances; molecules; Herschel observations; EXtra-Ordinary Sources; HEXOS; H2O; isotopologues; Orion KL;
    Academic Unit: Faculty of Science and Engineering > Experimental Physics
    Item ID: 4019
    Depositing User: Dr. Anthony Murphy
    Date Deposited: 04 Dec 2012 16:18
    Journal or Publication Title: Astronomy & Astrophysics
    Publisher: EDP Sciences
    Refereed: Yes
    Related URLs:
    URI: https://mural.maynoothuniversity.ie/id/eprint/4019
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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