Water abundance variations around high-mass protostars: HIFI observations of the DR21 region
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Water abundance variations around high-mass protostars : HIFI observations of the DR21 region. / WISH team.
I: Astronomy and Astrophysics, Bind 518, Nr. 4, L107, 15.10.2010.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Water abundance variations around high-mass protostars
T2 - HIFI observations of the DR21 region
AU - Van Der Tak, F. F.S.
AU - Marseille, M. G.
AU - Herpin, F.
AU - Wyrowski, F.
AU - Baudry, A.
AU - Bontemps, S.
AU - Braine, J.
AU - Doty, S.
AU - Frieswijk, W.
AU - Melnick, G.
AU - Shipman, R.
AU - Van Dishoeck, E. F.
AU - Benz, A. O.
AU - Caselli, P.
AU - Hogerheijde, M.
AU - Johnstone, D.
AU - Liseau, R.
AU - Bachiller, R.
AU - Benedettini, M.
AU - Bergin, E.
AU - Bjerkeli, P.
AU - Blake, G.
AU - Bruderer, S.
AU - Cernicharo, J.
AU - Codella, C.
AU - Daniel, F.
AU - Di Giorgio, A. M.
AU - Dominik, C.
AU - Encrenaz, P.
AU - Fich, M.
AU - Fuente, A.
AU - Giannini, T.
AU - Goicoechea, J.
AU - De Graauw, Th
AU - Helmich, F.
AU - Herczeg, G.
AU - Jørgensen, J.
AU - Kristensen, L.
AU - Larsson, B.
AU - Lis, D.
AU - McCoey, C.
AU - Neufeld, D.
AU - Nisini, B.
AU - Olberg, M.
AU - Parise, B.
AU - Pearson, J.
AU - Plume, R.
AU - Risacher, C.
AU - Santiago, J.
AU - Wampfler, S.
AU - WISH team
PY - 2010/10/15
Y1 - 2010/10/15
N2 - Context. Water is a key molecule in the star formation process, but its spatial distribution in star-forming regions is not well known. Aims. 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 H ii region. Methods. 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. Results. The dust continuum emission is extended over 36" FWHM, while the 13CO and H 2O 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 ∼2×10-10 for H2O and ∼8×10-7 for 13CO in the dense core, and higher H2O abundances of ∼4×10-9 in the foreground cloud and ∼7×10-7 in the outflow. Conclusions. 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.
AB - Context. Water is a key molecule in the star formation process, but its spatial distribution in star-forming regions is not well known. Aims. 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 H ii region. Methods. 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. Results. The dust continuum emission is extended over 36" FWHM, while the 13CO and H 2O 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 ∼2×10-10 for H2O and ∼8×10-7 for 13CO in the dense core, and higher H2O abundances of ∼4×10-9 in the foreground cloud and ∼7×10-7 in the outflow. Conclusions. 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.
KW - astrochemistry
KW - ISM: individual objects: DR21
KW - ISM: molecules
KW - stars: formation
UR - http://www.scopus.com/inward/record.url?scp=77957799846&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201014515
DO - 10.1051/0004-6361/201014515
M3 - Journal article
AN - SCOPUS:77957799846
VL - 518
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
SN - 0004-6361
IS - 4
M1 - L107
ER -
ID: 229737374