Determining the effect of a non-uniform AGB outflow on its chemistry

M. Van De Sande, J. O. Sundqvist, T. J. Millar, L. Decin

Research output: Contribution to journalArticlepeer-review


The molecular composition of the stellar outflows of AGB stars is determined by the stellar elemental carbon-to-oxygen abundance ratio, together with the physical circumstances in the innermost region of the outflow. Near the stellar surface, thermal equilibrium (TE) can be assumed. This leads to a certain molecular composition with a O- or C-rich signature. However, several molecular species have been detected that are not expected to be present in the inner region under the assumption of TE chemistry. As a solution to explain the presence of these unexpected species, non-equilibrium chemistry in the inner region of the outflow has been proposed. The outflows of AGB stars are generally not spherically symmetric or homogeneous, which influences the penetration of interstellar UV photons throughout the outflow. We investigate the effect of a clumpy, non-homogeneous outflow on the composition of the inner region by introducing a simple porosity formalism in our chemical model.

Original languageEnglish
Pages (from-to)43-46
JournalProceedings of the International Astronomical Union
Issue numberS332
Early online date04 Sep 2018
Publication statusPublished - 13 Sep 2018


  • astrochemistry
  • circumstellar matter
  • molecular processes
  • stars: AGB and post-AGB
  • stars: mass loss

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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