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Water abundance variations around high-mass protostars: HIFI observations of the DR21 region
- Source :
- Astronomy & Astrophysics, 518. EDP Sciences, Astronomy and Astrophysics-A&A, Astronomy and Astrophysics-A&A, EDP Sciences, 2010, 518, pp.L107. ⟨10.1051/0004-6361/201014515⟩, Astronomy & astrophysics, 518:107. EDP Sciences
- Publication Year :
- 2010
-
Abstract
- 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 1(11)-0(00) 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 ~2e-10 for H2O and ~8e-7 for 13CO in the dense core, and higher H2O abundances of ~4e-9 in the foreground cloud and ~7e-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.<br />Comment: Accepted by A&A Letters (Herschel special issue); 4 pages, 4 figures
- Subjects :
- 010504 meteorology & atmospheric sciences
LINE EMISSION
Continuum (design consultancy)
FOS: Physical sciences
CYGNUS-X
Astrophysics
01 natural sciences
Spectral line
STAR-FORMATION
RADIATIVE-TRANSFER
ISM: individual objects: DR21
YOUNG STARS
EXCITATION
0103 physical sciences
ABSORPTION
Radiative transfer
Protostar
Absorption (electromagnetic radiation)
010303 astronomy & astrophysics
QB
0105 earth and related environmental sciences
Line (formation)
H-2
Physics
stars: formation
astrochemistry
Star formation
[SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
MONTE-CARLO METHOD
Astronomy and Astrophysics
[PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR]
Astrophysics - Astrophysics of Galaxies
ISM: molecules
EVOLUTION
13. Climate action
Space and Planetary Science
Astrophysics of Galaxies (astro-ph.GA)
Outflow
Galaxy Astrophysics
Subjects
Details
- Language :
- English
- ISSN :
- 00046361
- Volume :
- 518
- Database :
- OpenAIRE
- Journal :
- Astronomy & Astrophysics
- Accession number :
- edsair.doi.dedup.....cc8f14d3d3a26014004c4c75e9e26746