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Trial run for importing the nublado.org Trac tickets as GitHub issues
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PDR chemistry on grain surfaces (trac #366) #368

Open cloudy-bot opened 7 years ago

cloudy-bot commented 7 years ago

reported by: @CloudyLex

Title:  
Surface chemistry in photodissociation regions
Authors:    
Esplugues, G. B.; Cazaux, S.; Meijerink, R.; Spaans, M.; Caselli, P.
Affiliation:    
AA(Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands esplugues@astro.rug.nl), AB(Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands), AC(Leiden Observatory, Leiden University, PO Box 9513, 2300 RA, Leiden, The Netherlands), AD(Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands), AE(Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748, Garching, Germany)
Publication:    
Astronomy & Astrophysics, Volume 591, id.A52, 18 pp. (A&A Homepage)
Publication Date:   
06/2016
Origin: 
EDP Sciences
Astronomy Keywords: 
astrochemistry, ISM: abundances, photon-dominated region
DOI:    
10.1051/0004-6361/201528001
Bibliographic Code: 
2016A&A...591A..52E
Abstract

Context. The presence of dust can strongly affect the chemical composition of 
the interstellar medium. We model the chemistry in photodissociation regions 
(PDRs) using both gas-phase and dust-phase chemical reactions. 

Aims: Our aim is to determine the chemical compositions of the interstellar 
medium (gas/dust/ice) in regions with distinct (molecular) gas densities that are 
exposed to radiation fields with different intensities. 

Methods: We have significantly improved the Meijerink PDR code by including 
3050 new gas-phase chemical reactions and also by implementing surface 
chemistry. In particular, we have included 117 chemical reactions occurring on 
grain surfaces covering different processes, such as adsorption, thermal 
desorption, chemical desorption, two-body reactions, photo processes, and 
cosmic-ray processes on dust grains. 

Results: We obtain abundances for different gas and solid species as a function 
of visual extinction, depending on the density and radiation field. We also analyse 
the rates of the formation of CO2 and H2O ices in different environments. In 
addition, we study how chemistry is affected by the presence/absence of ice 
mantles (bare dust or icy dust) and the impact of considering different desorption 
probabilities. 

Conclusions: The type of substrate (bare dust or icy dust) and the probability of 
desorption can significantly alter the chemistry occurring on grain surfaces, 
leading to differences of several orders of magnitude in the abundances of gas-
phase species, such as CO, H2CO, and CH3OH. The type of substrate, together 
with the density and intensity of the radiation field, also determine the threshold 
extinction to form ices of CO2 and H2O. We also conclude that H2CO and 
CH3OH are mainly released into the gas phase of low, far-ultraviolet illuminated 
PDRs through chemical desorption upon two-body surface reactions, rather than 
through photodesorption.

Migrated from https://www.nublado.org/ticket/366

{
    "status": "new",
    "changetime": "2019-02-04T13:02:49Z",
    "_ts": "1549285369825011",
    "description": "{{{\nTitle:\t\nSurface chemistry in photodissociation regions\nAuthors:\t\nEsplugues, G. B.; Cazaux, S.; Meijerink, R.; Spaans, M.; Caselli, P.\nAffiliation:\t\nAA(Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands esplugues@astro.rug.nl), AB(Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands), AC(Leiden Observatory, Leiden University, PO Box 9513, 2300 RA, Leiden, The Netherlands), AD(Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands), AE(Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, 85748, Garching, Germany)\nPublication:\t\nAstronomy & Astrophysics, Volume 591, id.A52, 18 pp. (A&A Homepage)\nPublication Date:\t\n06/2016\nOrigin:\t\nEDP Sciences\nAstronomy Keywords:\t\nastrochemistry, ISM: abundances, photon-dominated region\nDOI:\t\n10.1051/0004-6361/201528001\nBibliographic Code:\t\n2016A&A...591A..52E\nAbstract\n\nContext. The presence of dust can strongly affect the chemical composition of \nthe interstellar medium. We model the chemistry in photodissociation regions \n(PDRs) using both gas-phase and dust-phase chemical reactions. \n\nAims: Our aim is to determine the chemical compositions of the interstellar \nmedium (gas/dust/ice) in regions with distinct (molecular) gas densities that are \nexposed to radiation fields with different intensities. \n\nMethods: We have significantly improved the Meijerink PDR code by including \n3050 new gas-phase chemical reactions and also by implementing surface \nchemistry. In particular, we have included 117 chemical reactions occurring on \ngrain surfaces covering different processes, such as adsorption, thermal \ndesorption, chemical desorption, two-body reactions, photo processes, and \ncosmic-ray processes on dust grains. \n\nResults: We obtain abundances for different gas and solid species as a function \nof visual extinction, depending on the density and radiation field. We also analyse \nthe rates of the formation of CO2 and H2O ices in different environments. In \naddition, we study how chemistry is affected by the presence/absence of ice \nmantles (bare dust or icy dust) and the impact of considering different desorption \nprobabilities. \n\nConclusions: The type of substrate (bare dust or icy dust) and the probability of \ndesorption can significantly alter the chemistry occurring on grain surfaces, \nleading to differences of several orders of magnitude in the abundances of gas-\nphase species, such as CO, H2CO, and CH3OH. The type of substrate, together \nwith the density and intensity of the radiation field, also determine the threshold \nextinction to form ices of CO2 and H2O. We also conclude that H2CO and \nCH3OH are mainly released into the gas phase of low, far-ultraviolet illuminated \nPDRs through chemical desorption upon two-body surface reactions, rather than \nthrough photodesorption.\n}}}",
    "reporter": "gary",
    "cc": "",
    "resolution": "",
    "time": "2016-08-26T22:07:42Z",
    "component": "atomic/molecular data base",
    "summary": "PDR chemistry on grain surfaces",
    "priority": "good to do",
    "keywords": "",
    "version": "trunk",
    "milestone": "no milestone",
    "owner": "nobody",
    "type": "enhancement"
}
cloudy-bot commented 7 years ago

@peter-van-hoof-noaccount changed milestone from "" to "no milestone"