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Desorption Mechanism of Gases from Interstellar Grains and PAH Molecules

Published online by Cambridge University Press:  04 August 2017

A. Léger*
Affiliation:
Groupe de Physique des Solides de l'Ecole Normale Supérieure Université Paris 7, Tour 23, 2 place Jussieu 75251 PARIS 05

Abstract

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Many gases, including CO, should be condensed at the temperature of interstellar grains in the absence of efficient desorption mechanisms. We consider such mechanisms and find that impulsive heating by X rays and heavy cosmic rays (iron group) are the most efficient ones.

For CO rich mantles, we conclude that species as CO, N2, O2 and probably H2CO, NH3, H2O should be desorbed in most cases including dense and obscure regions. for mantles composed mainly of refractory ices (H2CO, NH3, H2O) we expect very little desorption.

The case of PAH molecules that may offer a larger surface for condensation than grains is also discussed.

Type
Grains
Copyright
Copyright © Reidel 1987 

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