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Nitrogen hydrides i...
Nitrogen hydrides in interstellar gas II. Analysis of Herschel/HIFI observations towards W49N and G10.6-0.4 (W31C)
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- Persson, Carina, 1964 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- De Luca, Massimo (författare)
- LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres, France
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- Mookerjea, B. (författare)
- Tata Institute of Fundamental Research
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- Olofsson, Henrik, 1972 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Black, John H, 1949 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Gerin, M. (författare)
- LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres, France
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- Herbst, E. (författare)
- University of Virginia
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- Bell, Tom A. (författare)
- Centro de Astrobiologia (CAB)
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- Coutens, A. (författare)
- Centre national de la recherche scientifique (CNRS),Université de Toulouse,University of Toulouse
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- Godard, B. (författare)
- Centro de Astrobiologia (CAB)
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- Goicoechea, J.R. (författare)
- Centro de Astrobiologia (CAB)
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- Hassel, G.E. (författare)
- Siena College
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- Hily-Blant, P. (författare)
- Université Grenoble Alpes,Grenoble Alpes University
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- Menten, K.M. (författare)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Muller, Holger (författare)
- Universität zu Köln,University of Cologne
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Pearson, T. J. (författare)
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Yu, S. (författare)
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(creator_code:org_t)
- 2012-07-12
- 2012
- Engelska.
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 543:Article Number: A145, s. 145-179
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Abstract
Ämnesord
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- As a part of the Herschel key programme PRISMAS, we have used the Herschel-HIFI instrument to observe interstellar nitrogen hydrides along the sight-lines towards eight high-mass star-forming regions in order to elucidate the production pathways leading to nitrogen-bearing species in diffuse gas. Here, we report observations towards W49N of the NH N = 1 - 0, J = 2 - 1, and J = 1 - 0, ortho-NH2 N_(Ka, K_c) J = 1_(1,1) 3/2 - 0_(0,0) 1/2, ortho-NH3 J_K = 1_0 - 0_0 and 2_0 - 1_0, para-NH3 J_K = 2_1 - 1_1 transitions, and unsuccessful searches for NH+. All detections show absorption by foreground material over a wide range of velocities, as well as absorption associated directly with the hot-core source itself. As in the previously published observations towards G10.6-0.4, the NH, NH2 and NH3 spectra towards W49N show strikingly similar and non-saturated absorption features. We decompose the absorption of the foreground material towards W49N into different velocity components in order to investigate whether the relative abundances vary among the velocity components, and, in addition, we re-analyse the absorption lines towards G10.6-0.4 in the same manner. Abundances, with respect to molecular hydrogen, in each velocity component are estimated using CH, which is found to correlate with H2 in the solar neighbourhood diffuse gas. The analysis points to a co-existence of the nitrogen hydrides in diffuse or translucent interstellar gaswith a high molecular fraction. Towards both sources, we find that NH is always at least as abundant as both o-NH2 and o-NH3, in sharp contrast to previous results for dark clouds. We find relatively constant N(NH)/N(o-NH3) and N(o-NH2)/N(o-NH3) ratios with mean values of 3.2 and 1.9 towards W49N, and 5.4 and 2.2 towards G10.6-0.4, respectively. The mean abundance of o-NH4 is ~2x10^-9 towards both sources. The nitrogen hydrides also show linear correlations with CN and HNC towards both sources, and looser correlations with CH. The upper limits on the NH+ abundance indicate column densities
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- ISM: molecules
- ISM: abundances
- Astrochemistry
- Molecular processes
- Sub-millimetre: ISM
- Line: formation
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- ref (ämneskategori)
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Persson, Carina, ...
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De Luca, Massimo
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Mookerjea, B.
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Olofsson, Henrik ...
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Black, John H, 1 ...
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Gerin, M.
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visa fler...
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Herbst, E.
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Bell, Tom A.
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Coutens, A.
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Godard, B.
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Goicoechea, J.R.
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Hassel, G.E.
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Hily-Blant, P.
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Menten, K.M.
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Muller, Holger
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Pearson, T. J.
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Yu, S.
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