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Herschel images of ...
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van Hoof, P. A. M.
(author)
Herschel images of NGC 6720 : H-2 formation on dust grains
- Article/chapterEnglish2010
Publisher, publication year, extent ...
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2010-07-16
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EDP Sciences,2010
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printrdacarrier
Numbers
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LIBRIS-ID:oai:DiVA.org:su-51697
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https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-51697URI
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https://doi.org/10.1051/0004-6361/201014590DOI
Supplementary language notes
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Language:English
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Summary in:English
Part of subdatabase
Classification
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Subject category:ref swepub-contenttype
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Subject category:art swepub-publicationtype
Notes
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authorCount :30
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Herschel PACS and SPIRE images have been obtained of NGC 6720 (the Ring nebula). This is an evolved planetary nebula with a central star that is currently on the cooling track, due to which the outer parts of the nebula are recombining. From the PACS and SPIRE images we conclude that there is a striking resemblance between the dust distribution and the H-2 emission, which appears to be observational evidence that H-2 forms on grain surfaces. We have developed a photoionization model of the nebula with the Cloudy code which we used to determine the physical conditions of the dust and investigate possible formation scenarios for the H-2. We conclude that the most plausible scenario is that the H-2 resides in high density knots which were formed after the recombination of the gas started when the central star entered the cooling track. Hydrodynamical instabilities due to the unusually low temperature of the recombining gas are proposed as a mechanism for forming the knots. H-2 formation in the knots is expected to be substantial after the central star underwent a strong drop in luminosity about one to two thousand years ago, and may still be ongoing at this moment, depending on the density of the knots and the properties of the grains in the knots.
Subject headings and genre
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planetary nebulae: individual: NGC 6720
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circumstellar matter
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dust
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extinction
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infrared: ISM
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ISM: molecules
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NATURAL SCIENCES
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NATURVETENSKAP
Added entries (persons, corporate bodies, meetings, titles ...)
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Van de Steene, G. C.
(author)
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Barlow, M. J.
(author)
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Exter, K. M.
(author)
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Sibthorpe, B.
(author)
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Ueta, T.
(author)
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Peris, V.
(author)
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Groenewegen, M. A. T.
(author)
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Blommaert, J. A. D. L.
(author)
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Cohen, M.
(author)
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De Meester, W.
(author)
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Ferland, G. J.
(author)
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Gear, W. K.
(author)
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Gomez, H. L.
(author)
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Hargrave, P. C.
(author)
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Huygen, E.
(author)
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Ivison, R. J.
(author)
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Jean, C.
(author)
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Leeks, S. J.
(author)
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Lim, T. L.
(author)
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Olofsson, GöranStockholms universitet,Institutionen för astronomi(Swepub:su)olofsson
(author)
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Polehampton, E. T.
(author)
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Regibo, S.
(author)
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Royer, P.
(author)
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Swinyard, B. M.
(author)
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Vandenbussche, B.
(author)
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Van Winckel, H.
(author)
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Waelkens, C.
(author)
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Walker, H. J.
(author)
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Wesson, R.
(author)
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Stockholms universitetInstitutionen för astronomi
(creator_code:org_t)
Related titles
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In:Astronomy and Astrophysics: EDP Sciences518, s. L137-0004-63611432-0746
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van Hoof, P. A. ...
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Van de Steene, G ...
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Barlow, M. J.
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Exter, K. M.
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Sibthorpe, B.
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Ueta, T.
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Peris, V.
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Groenewegen, M. ...
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Blommaert, J. A. ...
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Cohen, M.
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De Meester, W.
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Ferland, G. J.
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Gear, W. K.
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Gomez, H. L.
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Hargrave, P. C.
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Huygen, E.
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Ivison, R. J.
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Jean, C.
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Leeks, S. J.
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Lim, T. L.
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Olofsson, Göran
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Polehampton, E. ...
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Regibo, S.
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Royer, P.
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Swinyard, B. M.
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Vandenbussche, B ...
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Van Winckel, H.
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Waelkens, C.
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Walker, H. J.
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Wesson, R.
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Stockholm University