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Molecular Carbon Chains and Rings in TMC-1
David Fossé,José Cernicharo,Maryvonne Gerin, andPierre Cox
© 2001. The AmericanAstronomical Society. All rights reserved. Printed inU.S.A.
The Astrophysical Journal,Volume 552,Number 1Citation David Fosséet al 2001ApJ552 168DOI 10.1086/320471
David Fossé
AFFILIATIONS
Depto Física Molecular, Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Serrano 121, E-28006 Madrid, Spain
Laboratoire de Radioastronomie Millimétrique, Observatoire de Paris and Ecole Normale Supérieure, 24 rue Lhomond, F-75231 Paris, CEDEX 05, France
José Cernicharo
AFFILIATIONS
Depto Física Molecular, Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas, Serrano 121, E-28006 Madrid, Spain
Maryvonne Gerin
AFFILIATIONS
Laboratoire de Radioastronomie Millimétrique, Observatoire de Paris and Ecole Normale Supérieure, 24 rue Lhomond, F-75231 Paris, CEDEX 05, France
Pierre Cox
AFFILIATIONS
Institut d’Astrophysique Spatiale, Université de Paris-Sud, Bâtiment 121, F-91405 Orsay, France
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- Received2000 April 18
- Accepted2001 January 3
Abstract
We present mapping results in several rotational transitions of HC3N, C6H, both cyclic and linear C3H2 and C3H, toward the cyanopolyyne peak of the filamentary dense cloud TMC-1 using the IRAM 30 m and MPIfR 100 m telescopes. The spatial distribution of the cumulene carbon chain propadienylidene H2CCC (hereafterl-C3H2) is found to deviate significantly from the distributions of the cyclic isomerc-C3H2, HC3N, and C6H, which, in turn, look very similar. The cyclic over linear abundance ratio of C3H2 increases by a factor of 3 across the filament, with a value of 28 at the cyanopolyyne peak. This abundance ratio is an order of magnitude larger than the range (3-5) we observed in the diffuse interstellar medium. The cyclic over linear abundance ratio of C3H also varies by ~2.5 in TMC-1, reaching a maximum value (13) close to the cyanopolyyne peak. These behaviors might be related to competitive processes between ion-neutral and neutral-neutral reactions for cyclic and linear species.