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LIBRIS Formathandbok  (Information om MARC21)
FältnamnIndikatorerMetadata
00004140naa a2200433 4500
001oai:research.chalmers.se:ff08fb4b-8e2e-48c9-b4d0-81c4cfdca1b5
003SwePub
008171007s2011 | |||||||||||000 ||eng|
024a https://doi.org/10.1051/0004-6361/2010160792 DOI
024a https://research.chalmers.se/publication/1442642 URI
040 a (SwePub)cth
041 a engb eng
042 9 SwePub
072 7a art2 swepub-publicationtype
072 7a ref2 swepub-contenttype
100a Suutarinen, A.u Helsingin Yliopisto,University of Helsinki4 aut
2451 0a CH abundance gradient in TMC-1
264 c 2011-06-27
264 1b EDP Sciences,c 2011
520 a Aims. The aim of this study is to examine if the well-known chemical gradient in TMC-1 is reflected in the amount of rudimentaryforms of carbon available in the gas-phase. As a tracer we use the CH radical which is supposed to be well correlated with carbonatoms and simple hydrocarbon ions.Methods. We observed the 9-cm Λ-doubling lines of CH along the dense filament of TMC-1. The CH column densities were comparedwith the total H2 column densities derived using the 2MASS NIR data and previously published SCUBA maps and with OH columndensities derived using previous observations with Effelsberg. We also modelled the chemical evolution of TMC-1 adopting physicalconditions typical of dark clouds using the UMIST Database for Astrochemistry gas-phase reaction network to aid the interpretationof the observed OH/CH abundance ratios.Results. The CH column density has a clear peak in the vicinity of the cyanopolyyne maximum of TMC-1. The fractional CHabundance relative to H2 increases steadily from the northwestern end of the filament where it lies around 1.0 × 10−8, to the southeastwhere it reaches a value of 2.0 × 10−8. The OH and CH column densities are well correlated, and we obtained OH/CH abundanceratios of ∼16–20. These values are clearly larger than what has been measured recently in diffuse interstellar gas and is likely to berelated to C to CO conversion at higher densities. The good correlation between CH and OH can be explained by similar productionand destruction pathways. We suggest that the observed CH and OH abundance gradients are mainly due to enhanced abundances ina low-density envelope which becomes more prominent in the southeastern part and seems to continue beyond the dense filament.Conclusions. An extensive envelope probably signifies an early stage of dynamical evolution, and conforms with the detection of alarge CH abundance in the southeastern part of the cloud. The implied presence of other simple forms of carbon in the gas phase provides a natural explanation for the observation of "early-type" molecules in this region.
650 7a NATURVETENSKAPx Fysikx Astronomi, astrofysik och kosmologi0 (SwePub)103052 hsv//swe
650 7a NATURAL SCIENCESx Physical Sciencesx Astronomy, Astrophysics and Cosmology0 (SwePub)103052 hsv//eng
653 a individual objects: TMC-1
653 a abundances:ISM
653 a astrochemistry-ISM
700a Geppert, W.D.4 aut
700a Harju, J.u Helsingin Yliopisto,University of Helsinki4 aut
700a Heikkilä, Arto,d 1965u Chalmers tekniska högskola,Chalmers University of Technology4 aut0 (Swepub:cth)artoh
700a Hotzel, S.u Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) Mbh,Helsingin Yliopisto,University of Helsinki4 aut
700a Juvela, M.u Helsingin Yliopisto,University of Helsinki4 aut
700a Millar, T.J.u Queen's University Belfast4 aut
700a Walsh, C.u Queen's University Belfast4 aut
700a Wouterloot, J.G.A4 aut
710a Helsingin Yliopistob Chalmers tekniska högskola4 org
773t Astronomy and Astrophysicsd : EDP Sciencesg 531, s. A121-q 531<A121-x 0004-6361x 1432-0746
856u http://dx.doi.org/10.1051/0004-6361/201016079y FULLTEXT
856u https://www.aanda.org/articles/aa/pdf/2011/07/aa16079-10.pdf
8564 8u https://doi.org/10.1051/0004-6361/201016079
8564 8u https://research.chalmers.se/publication/144264

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