2010A&A...521L..28E

Query : 2010A&A...521L..28E

2010A&A...521L..28E - Astronomy and Astrophysics, volume 521, L28-28 (2010/10-1)

The distribution of water in the high-mass star-forming region NGC 6334 I.

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. and YORKE H.

Abstract (from CDS):

We present observations of twelve rotational transitions of H₂¹⁶O, H₂¹⁸O, and H₂¹⁷O 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. We identify three main gas components (hot core, cold foreground, and outflow) in NGC 6334 I and derive the physical conditions in these components. The hot core, identified by the emission in highly excited lines, shows a high excitation temperature of ∼200K, whereas water in the foreground component is predominantly in the ortho- and para- ground states. The abundance of water varies between 4x10^–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 H₂¹⁸O/H₂¹⁷O 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).

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Journal keyword(s): stars: formation - ISM: molecules

Simbad objects: 4

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Number of rows : 4

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Sp type	#ref 1850 - 2023	#notes
1	NGC 6334	HII	17 20 53	-36 07.9	~	674	0
2	NAME NGC 6334-I	Cl*	17 20 53.35	-35 47 01.5	~	333	0
3	NAME Sgr B2 Main	Rad	17 47 20.5	-28 23 06	~	390	1
4	DR 21	SFR	20 39 01.6	+42 19 38	O4.5	1036	0

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