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The chemistry in clumpy AGB outflows

Published online by Cambridge University Press:  30 December 2019

M. Van de Sande Open the ORCID record for M. Van de Sande [Opens in a new window] ,
J. O. Sundqvist ,
T. J. Millar ,
D. Keller  and
L. Decin
M. Van de Sande
Affiliation:
Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium email: marie.vandesande@kuleuven.be
J. O. Sundqvist
Affiliation:
Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium email: marie.vandesande@kuleuven.be
T. J. Millar
Affiliation:
Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN, UK
D. Keller
Affiliation:
Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium email: marie.vandesande@kuleuven.be
L. Decin
Affiliation:
Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium email: marie.vandesande@kuleuven.be School of Physics and Astronomy University of Leeds, Leeds LS2 9JT, UK
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Abstract

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The chemistry within the outflow of an AGB star is determined by its elemental C/O abundance ratio. Thanks to the advent of high angular resolution observations, it is clear that most outflows do not have a smooth density distribution, but are inhomogeneous or “clumpy”. We have developed a chemical model that takes into account the effect of a clumpy outflow on its gas-phase chemistry by using a theoretical porosity formalism. The clumpiness of the model increases the inner wind abundances of all so-called unexpected species, i.e. species that are not predicted to be present assuming an initial thermodynamic equilibrium chemistry. By applying the model to the distribution of cyanopolyynes and hydrocarbon radicals within the outflow of IRC+10216, we find that the chemistry traces the underlying density distribution.

Keywords

astrochemistrymolecular processesstars: AGB and post-AGB starscircumstellar materialstars: mass lossstars: individual (IRC+10216)
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 14 , Symposium S343: Why Galaxies Care About AGB Stars: A Continuing Challenge through Cosmic Time , August 2018 , pp. 531 - 532
Copyright
© International Astronomical Union 2019 

References

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