Water and ammonia abundances in S140 with the Odin satellite

Autor: A. O. H. Olofsson, Aa. Sandqvist, Carina M. Persson, Marco Spaans, T. Liljestrom, Åke Hjalmarson, D. R. Poelman, John H. Black, Urban Frisk, Michael Olberg
Přispěvatelé: Astronomy
Jazyk: angličtina
Rok vydání: 2009
Předmět:
WAVE-ASTRONOMY-SATELLITE
010504 meteorology & atmospheric sciences
FOS: Physical sciences
Astrophysics
PHOTON-DOMINATED REGION
GAS-PHASE H2O
1ST DETECTION
MASSIVE PROTOSTARS
MOLECULAR CLOUD
01 natural sciences
ISM: abundances
Ammonia
chemistry.chemical_compound
Abundance (ecology)
0103 physical sciences
submillimeter
010303 astronomy & astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
0105 earth and related environmental sciences
Line (formation)
Physics
STAR-FORMING REGIONS
SPECTRAL-LINE SURVEY
Astronomy and Astrophysics
line: profiles
Line width
ISM: molecules
ORION-KL
BANDS 486-492
chemistry
Astrophysics - Solar and Stellar Astrophysics
13. Climate action
Space and Planetary Science
Homogeneous
ISM: individual objects: S140
Outflow
Satellite
line: formation
Intensity (heat transfer)
Zdroj: Astronomy & astrophysics, 494(2), 637-646. EDP Sciences
ISSN: 1432-0746
0004-6361
Popis: We have used the Odin satellite to obtain strip maps of the ground-state rotational transitions of ortho-water and ortho-ammonia, as well as CO(5-4) and 13CO(5-4) across the PDR, and H218O in the central position. A physi-chemical inhomogeneous PDR model was used to compute the temperature and abundance distributions for water, ammonia and CO. A multi-zone escape probability method then calculated the level populations and intensity distributions. These results are compared to a homogeneous model computed with an enhanced version of the RADEX code. H2O, NH3 and 13CO show emission from an extended PDR with a narrow line width of ~3 kms. Like CO, the water line profile is dominated by outflow emission, however, mainly in the red wing. The PDR model suggests that the water emission mainly arises from the surfaces of optically thick, high density clumps with n(H2)>10^6 cm^-3 and a clump water abundance, with respect to H2, of 5x10^-8. The mean water abundance in the PDR is 5x10^-9, and between ~2x10^-8 -- 2x10^-7 in the outflow derived from a simple two-level approximation. Ammonia is also observed in the extended clumpy PDR, likely from the same high density and warm clumps as water. The average ammonia abundance is about the same as for water: 4x10^-9 and 8x10^-9 given by the PDR model and RADEX, respectively. The similarity of water and ammonia PDR emission is also seen in the almost identical line profiles observed close to the bright rim. Around the central position, ammonia also shows some outflow emission although weaker than water in the red wing. Predictions of the H2O(110-101) and (111-000) antenna temperatures across the PDR are estimated with our PDR model for the forthcoming observations with the Herschel Space Observatory.
13 pages, 14 figures, 10 tables. Accepted for publication in Astronomy & Astrophysics 14 November 2008
Databáze: OpenAIRE
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