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Galactic Bulge PNe: Carbon molecules in oxygen-rich environments

Published online by Cambridge University Press:  30 August 2012

Lizette Guzmán-Ramírez
Affiliation:
Jodrell Bank Centre for Astrophysics, School of Physics & Astronomy, The University of Manchester, Manchester, M13 9PL, UK email: lizette.ramirez@postgrad.manchester.ac.uk
Albert Zijlstra
Affiliation:
Jodrell Bank Centre for Astrophysics, School of Physics & Astronomy, The University of Manchester, Manchester, M13 9PL, UK email: lizette.ramirez@postgrad.manchester.ac.uk
Roisin Níchuimín
Affiliation:
Jodrell Bank Centre for Astrophysics, School of Physics & Astronomy, The University of Manchester, Manchester, M13 9PL, UK email: lizette.ramirez@postgrad.manchester.ac.uk
Krzysztof Gesicki
Affiliation:
Centrum Astronomii UMK, ul.Gagarina 11, 87-100 Torun, Poland
Eric Lagadec
Affiliation:
European Southern Observatory, Karl-Schwarzschild-Str 2, 85748 Garching, Germany
Tom J. Millar
Affiliation:
Astrophysics Research Centre, Queen's University Belfast, Belfast BT7 1NN, UK
Paul M. Woods
Affiliation:
Dept. of Physics and Astronomy, University College London, Gower Street, London WC1E6BT, UK
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Abstract

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Galactic bulge planetary nebulae show evidence of mixed chemistry with emission from both silicate dust and PAHs. This mixed chemistry is unlikely to be related to carbon dredge up, as third dredge-up is not expected to occur in the low mass bulge stars. We show that the phenomenon is widespread, and is seen in 30 nebulae out of our sample of 40. A strong correlation is found between strength of the PAH bands and morphology, in particular, the presence of a dense torus. A chemical model is presented which shows that hydrocarbon chains can form within oxygen-rich gas through gas-phase chemical reactions. We conclude that the mixed chemistry phenomenon occurring in the galactic bulge planetary nebulae is best explained through hydrocarbon chemistry in an UV-irradiated, dense torus.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2012

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