2010A&A...521L..32M

Query : 2010A&A...521L..32M

2010A&A...521L..32M - Astronomy and Astrophysics, volume 521, L32-32 (2010/10-1)

Water abundances in high-mass protostellar envelopes: Herschel observations with HIFI.

MARSEILLE M.G., VAN DER TAK F.F.S., HERPIN F., WYROWSKI F., CHAVARRIA L., PIETROPAOLI B., BAUDRY A., BONTEMPS S., CERNICHARO J., JACQ T., FRIESWIJK W., SHIPMAN R., VAN DISHOECK E.F., BACHILLER R., BENEDETTINI M., BENZ A.O., BERGIN E., BJERKELI P., BLAKE G.A., BRAINE J., BRUDERER S., CASELLI P., CAUX E., CODELLA C., DANIEL F., DIELEMAN P., DI GIORGIO A.M., DOMINIK C., DOTY S.D., ENCRENAZ P., FICH M., FUENTE A., GAIER T., GIANNINI T., GOICOECHEA J.R., DE GRAAUW T., HELMICH F., HERCZEG G.J., HOGERHEIJDE M.R., JACKSON B., JAVADI H., JELLEMA W., JOHNSTONE D., JORGENSEN J.K., KESTER D., KRISTENSEN L.E., LARSSON B., LAAUWEN W., LIS D., LISEAU R., LUINGE W., McCOEY C., MEGEJ A., MELNICK G., NEUFELD D., NISINI B., OLBERG M., PARISE B., PEARSON J.C., PLUME R., RISACHER C., ROELFSEMA P., SANTIAGO-GARCIA J., SARACENO P., SIEGEL P., STUTZKI J., TAFALLA M., VAN KEMPEN T.A., VISSER R., WAMPFLER S.F. and YILDIZ U.A.

Abstract (from CDS):

We derive the dense core structure and the water abundance in four massive star-forming regions in the hope of understanding the earliest stages of massive star formation. We present Herschel/HIFI observations of the para-H₂O1₁₁-0₀₀ and 2₀₂-1₁₁ and the para-H₂¹⁸O 1₁₁-0₀₀ transitions. The envelope contribution to the line profiles is separated from contributions by outflows and foreground clouds. The envelope contribution is modeled with Monte-Carlo radiative transfer codes for dust and molecular lines (MC3D and RATRAN), and the water abundance and the turbulent velocity width as free parameters. While the outflows are mostly seen in emission in high-J lines, envelopes are seen in absorption in ground-state lines, which are almost saturated. The derived water abundances range from 5x10^–10 to 4x10^–8 in the outer envelopes. We detect cold clouds surrounding the protostar envelope, thanks to the very high quality of the Herschel/HIFI data and the unique ability of water to probe them. Several foreground clouds are also detected along the line of sight. The low H₂O abundances in massive dense cores are in accordance with the expectation that high densities and low temperatures lead to freeze-out of water on dust grains. The spread in abundance values is not clearly linked to physical properties of the sources.

Abstract Copyright: ∼

Journal keyword(s): dust, extinction - ISM: molecules - ISM: abundances

Simbad objects: 7

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Number of rows : 7

N	Identifier	Otype	ICRS (J2000) RA	ICRS (J2000) DEC	Sp type	#ref 1850 - 2024
1	NAME W3 IRS 5	Y*O	02 25 40.54	+62 05 51.4	B1	350
2	W 33a	Y*O	18 14 39.56547	-17 52 02.2260	~	688
3	CORNISH G029.9559-00.0168	Y*O	18 46 04.18	-02 39 21.3	~	364
4	SNR G030.8-00.0	SNR	18 47 32	-01 56.5	~	520
5	IRAS 18449-0115	cor	18 47 34.29	-01 12 44.5	~	378
6	AGAL G030.818-00.056	cor	18 47 47.0	-01 54 28	~	153
7	DR 21	SFR	20 39 01.6	+42 19 38	O4.5	1045

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