2010A&A...518L.107V

Query : 2010A&A...518L.107V

2010A&A...518L.107V - Astronomy and Astrophysics, volume 518, L107-107 (2010/7-2)

Water abundance variations around high-mass protostars: HIFI observations of the DR 21 region.

VAN DER TAK F.F.S., MARSEILLE M., HERPIN F., WYROWSKI F., BAUDRY A., BONTEMPS S., BRAINE J., DOTY S.D., FRIESWIJK W., MELNICK G., SHIPMAN R., VAN DISHOECK E.F., BENZ A.O., CASELLI P., HOGERHEIJDE M., JOHNSTONE D., LISEAU R., BACHILLER R., BENEDETTINI M., BERGIN E., BJERKELI P., BLAKE G., BRUDERER S., CERNICHARO J., CODELLA C., DANIEL F., DI GIORGIO A.M., DOMINIK C., ENCRENAZ P., FICH M., FUENTE A., GIANNINI T., GOICOECHEA J.R., DE GRAAUW T., HELMICH F., HERCZEG G., JORGENSEN J., KRISTENSEN L., LARSSON B., LIS D., McCOEY C., NEUFELD D., NISINI B., OLBERG M., PARISE B., PEARSON J., PLUME R., RISACHER C., SANTIAGO J., SARACENO P., TAFALLA M., VAN KEMPEN T., VISSER R., WAMPFLER S., YILDIZ U., RAVERA L., ROELFSEMA P., SIEBERTZ O. and TEYSSIER D.

Abstract (from CDS):

Water is a key molecule in the star formation process, but its spatial distribution in star-forming regions is not well known. We study the distribution of dust continuum and H₂O and ¹³CO line emission in DR21, a luminous star-forming region with a powerful outflow and a compact HII region. Herschel-HIFI spectra near 1100 GHz show narrow ¹³CO 10-9 emission and H₂O 1₁₁-0₀₀ absorption from the dense core and broad emission from the outflow in both lines. The H₂O line also shows absorption by a foreground cloud known from ground-based observations of low-J CO lines. The dust continuum emission is extended over 36'' FWHM, while the ¹³CO and H₂O lines are confined to ≃24'' or less. The foreground absorption appears to peak further North than the other components. Radiative transfer models indicate very low abundances of ∼2x10^–10 for H₂O and ∼8x10^–7 for ¹³CO in the dense core, and higher H₂O abundances of ∼4x10^–9 in the foreground cloud and ∼7x10^–7 in the outflow. The high H₂O abundance in the warm outflow is probably due to the evaporation of water-rich icy grain mantles, while the H₂O abundance is kept down by freeze-out in the dense core and by photodissociation in the foreground cloud.

Abstract Copyright: ∼

Journal keyword(s): ISM: molecules - stars: formation - astrochemistry - ISM: individual objects: DR21

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	NAME Cyg X	Cld	20 28 41	+41 10.2	~	765	1
2	NAME Cyg X FIR 33	Y*O	20 38 35.9	+42 37 22	B1.5	384	1
3	NAME DR 21(OH) M	Rad	20 39 01	+42 29.8	~	87	0
4	GRS G081.70 +00.50	SFR	20 39 01.6	+42 19 38	O4.5	1019	0

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