Space Science Reviews

, Volume 156, Issue 1, pp 13–72

Reaction Networks for Interstellar Chemical Modelling: Improvements and Challenges

  • V. Wakelam
  • I. W. M. Smith
  • E. Herbst
  • J. Troe
  • W. Geppert
  • H. Linnartz
  • K. Öberg
  • E. Roueff
  • M. Agúndez
  • P. Pernot
  • H. M. Cuppen
  • J. C. Loison
  • D. Talbi
Open AccessArticle

DOI: 10.1007/s11214-010-9712-5

Cite this article as:
Wakelam, V., Smith, I.W.M., Herbst, E. et al. Space Sci Rev (2010) 156: 13. doi:10.1007/s11214-010-9712-5

Abstract

We survey the current situation regarding chemical modelling of the synthesis of molecules in the interstellar medium. The present state of knowledge concerning the rate coefficients and their uncertainties for the major gas-phase processes—ion-neutral reactions, neutral-neutral reactions, radiative association, and dissociative recombination—is reviewed. Emphasis is placed on those key reactions that have been identified, by sensitivity analyses, as ‘crucial’ in determining the predicted abundances of the species observed in the interstellar medium. These sensitivity analyses have been carried out for gas-phase models of three representative, molecule-rich, astronomical sources: the cold dense molecular clouds TMC-1 and L134N, and the expanding circumstellar envelope IRC +10216. Our review has led to the proposal of new values and uncertainties for the rate coefficients of many of the key reactions. The impact of these new data on the predicted abundances in TMC-1 and L134N is reported. Interstellar dust particles also influence the observed abundances of molecules in the interstellar medium. Their role is included in gas-grain, as distinct from gas-phase only, models. We review the methods for incorporating both accretion onto, and reactions on, the surfaces of grains in such models, as well as describing some recent experimental efforts to simulate and examine relevant processes in the laboratory. These efforts include experiments on the surface-catalyzed recombination of hydrogen atoms, on chemical processing on and in the ices that are known to exist on the surface of interstellar grains, and on desorption processes, which may enable species formed on grains to return to the gas-phase.

Keywords

AstrochemistryReaction rate coefficientsGas-phase chemistryGrain-surface chemistryChemical modellingUncertainty propagationSensitivity analysis
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© The Author(s) 2010

Authors and Affiliations

  • V. Wakelam
    • 1
    • 2
  • I. W. M. Smith
    • 3
  • E. Herbst
    • 4
  • J. Troe
    • 5
    • 6
  • W. Geppert
    • 7
  • H. Linnartz
    • 8
  • K. Öberg
    • 8
    • 9
  • E. Roueff
    • 10
  • M. Agúndez
    • 11
  • P. Pernot
    • 12
    • 13
  • H. M. Cuppen
    • 8
  • J. C. Loison
    • 14
  • D. Talbi
    • 15
  1. 1.Observatoire Aquitain des Sciences de l’UniversUniversité de BordeauxFloirac CedexFrance
  2. 2.Laboratoire d’Astrophysique de BordeauxCNRS, UMR 5804Floirac CedexFrance
  3. 3.University Chemical LaboratoriesCambridgeUK
  4. 4.Departments of Physics, Astronomy, and ChemistryThe Ohio State UniversityColumbusUSA
  5. 5.Institut für Physikalische ChemieUniversität GöttingenGöttingenGermany
  6. 6.Max-Planck-Institut für Biophysikalische ChemieGöttingenGermany
  7. 7.Department of PhysicsUniversity of StockholmStockholmSweden
  8. 8.Sackler Laboratory for Astrophysics, Leiden ObservatoryUniversity of LeidenLeidenThe Netherlands
  9. 9.Harvard-Smithsonian Center for AstrophysicsCambridgeUSA
  10. 10.Universit Paris 7 and Observatoire de Paris, LUTH, UMR 8102 CNRSMeudonFrance
  11. 11.Observatoire de Paris-MeudonLUTHMeudonFrance
  12. 12.Univ Paris-Sud, Laboratoire de Chimie PhysiqueUMR 8000OrsayFrance
  13. 13.CNRSOrsayFrance
  14. 14.Institut des Sciences Moléculaires, CNRS UMR 5255Université Bordeaux ITalence cedexFrance
  15. 15.Université Montpellier II—GRAALCNRS-UMR 5024MontpellierFrance