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Herschel/HIFI obser...
Herschel/HIFI observations of the circumstellar ammonia lines in IRC+10216
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- Schmidt, M. R. (författare)
- Polish Academy of Sciences
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- He, J. H. (författare)
- Chinese Academy of Sciences
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- Szczerba, R. (författare)
- Polish Academy of Sciences
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- Bujarrabal, V. (författare)
- Observatorio Astronómico Nacional (OAN),Spanish National Observatory (OAN)
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- Alcolea, J. (författare)
- Observatorio Astronómico Nacional (OAN),Spanish National Observatory (OAN)
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- Cernicharo, J. (författare)
- CSIC - Instituto de Ciencia de Materiales de Madrid (ICMM)
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- Decin, L. (författare)
- Universiteit Van Amsterdam,University of Amsterdam,Katholieke Universiteit Leuven
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- Justtanont, Kay, 1965 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Teyssier, D. (författare)
- European Space Astronomy Centre (ESAC)
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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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- Neufeld, D. A. (författare)
- Johns Hopkins University
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- Olofsson, Hans, 1952 (författare)
- Stockholms universitet,Institutionen för astronomi,Chalmers University of Technology, Sweden,Chalmers tekniska högskola
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- Planesas, P. (författare)
- Observatorio Astronómico Nacional (OAN),Spanish National Observatory (OAN),European Space Astronomy Centre (ESAC)
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Marston, A. P. (författare)
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- Sobolev, A. M. (författare)
- Ural Federal University
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- de Koter, A. (författare)
- Universiteit Van Amsterdam,University of Amsterdam
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- Schöier, Fredrik, 1969 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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(creator_code:org_t)
- 2016-08-12
- 2016
- Engelska.
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 592
- Relaterad länk:
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http://publications.... (primary) (free)
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Context. A discrepancy exists between the abundance of ammonia (NH3) derived previously for the circumstellar envelope (CSE) of IRC+10216 from far-IR submillimeter rotational lines and that inferred from radio inversion or mid-infrared (MIR) absorption transitions. Aims. To address the discrepancy described above, new high-resolution far-infrared (FIR) observations of both ortho-and para-NH3 transitions toward IRC+10216 were obtained with Herschel, with the goal of determining the ammonia abundance and constraining the distribution of NH3 in the envelope of IRC+10216. Methods. We used the Heterodyne Instrument for the Far Infrared (HIFI) on board Herschel to observe all rotational transitions up to the J = 3 level (three ortho-and six para-NH3 lines). We conducted non-LTE multilevel radiative transfer modelling, including the effects of near-infrared (NIR) radiative pumping through vibrational transitions. The computed emission line profiles are compared with the new HIFI data, the radio inversion transitions, and the MIR absorption lines in the nu(2) band taken from the literature. Results. We found that NIR pumping is of key importance for understanding the excitation of rotational levels of NH3. The derived NH3 abundances relative to molecular hydrogen were (2.8 +/- 0.5) x 10(-8) for ortho-NH3 and (3.2(-0.6)(+0.7)) x 10(-8) for para-NH3, consistent with an ortho/para ratio of 1. These values are in a rough agreement with abundances derived from the inversion transitions, as well as with the total abundance of NH3 inferred from the MIR absorption lines. To explain the observed rotational transitions, ammonia must be formed near to the central star at a radius close to the end of the wind acceleration region, but no larger than about 20 stellar radii (1 sigma confidence level).
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- stars: AGB and post-AGB
- circumstellar matter
- stars: carbon
- stars: individual: IRC+10216
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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Till lärosätets databas
- Av författaren/redakt...
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Schmidt, M. R.
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He, J. H.
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Szczerba, R.
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Bujarrabal, V.
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Alcolea, J.
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Cernicharo, J.
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visa fler...
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Decin, L.
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Justtanont, Kay, ...
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Teyssier, D.
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Menten, K. M.
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Neufeld, D. A.
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Olofsson, Hans, ...
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Planesas, P.
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Marston, A. P.
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Sobolev, A. M.
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de Koter, A.
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Schöier, Fredrik ...
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visa färre...
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Stockholms universitet
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Chalmers tekniska högskola