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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 559177.0, MPI für Astronomie / Publikationen_mpia
The distribution of water in the high-mass star-forming region NGC 6334 I
Authors:Emprechtinger, M.; Lis, D. C.; Bell, T.; Phillips, T. G.; Schilke, P.; Comito, C.; Rolffs, R.; van der Tak, F.; Ceccarelli, C.; Aarts, H.; Bacmann, A.; Baudry, A.; Benedettini, M.; Bergin, E. A.; Blake, G.; Boogert, A.; Bottinelli, S.; Cabrit, S.; Caselli, P.; Castets, A.; Caux, E.; Cernicharo, J.; Codella, C.; Coutens, A.; Crimier, N.; Demyk, K.; Dominik, C.; Encrenaz, P.; Falgarone, E.; Fuente, A.; Gerin, M.; Goldsmith, P.; Helmich, F.; Hennebelle, P.; Henning, T.; Herbst, E.; Hily-Blant, P.; Jacq, T.; Kahane, C.; Kama, M.; Klotz, A.; Kooi, J.; Langer, W.; Lefloch, B.; Loose, A.; Lord, S.; Lorenzani, A.; Maret, S.; Melnick, G.; Neufeld, D.; Nisini, B.; Ossenkopf, V.; Pacheco, S.; Pagani, L.; Parise, B.; Pearson, J.; Risacher, C.; Salez, M.; Saraceno, P.; Schuster, K.; Stutzki, J.; Tielens, X.; van der Wiel, M.; Vastel, C.; Viti, S.; Wakelam, V.; Walters, A.; Wyrowski, F.; Yorke, H.
Date of Publication (YYYY-MM-DD):2010
Journal Abbrev.:Astronomy and Astrophysics
Start Page:id.L28
Audience:Not Specified
Abstract / Description:<BR /> Aims: We present observations of twelve rotational transitions of H_216O, H_218O, and H_217O toward the massive star-forming region NGC 6334 I, carried out with Herschel/HIFI as part of the guaranteed time key program Chemical HErschel Surveys of Star forming regions (CHESS). We analyze these observations to obtain insights into physical processes in this region. <BR /> Methods: We identify three main gas components (hot core, cold foreground, and outflow) in NGC 6334 I and derive the physical conditions in these components. <BR /> Results: The hot core, identified by the emission in highly excited lines, shows a high excitation temperature of ~200 K, whereas water in the foreground component is predominantly in the ortho- and para- ground states. The abundance of water varies between 4 × 10-5 (outflow) and 10-8 (cold foreground gas). This variation is most likely due to the freeze-out of water molecules onto dust grains. The H_218O/H_217O abundance ratio is 3.2, which is consistent with the 18O/17O ratio determined from CO isotopologues. The ortho/para ratio in water appears to be relatively low (1.6±1) in the cold, quiescent gas, but close to the equilibrium value of three in the warmer outflow material (2.5±0.8). Herschel is an ESA space observatory with science instruments provided by European-led principal Investigator consortia and with important participation from NASA.Figures 1, 2 and 3 and Tables 2-4 (pages 5 to 6) are only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A>
Free Keywords:stars: formation; ISM: molecules
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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