Desorption of CO and O2 interstellar ice analogs

K. Acharyya, G.W. Fuchs, H.J. Fraser, E.F. van Dishoeck, H. Linnartz

Research output: Contribution to journalArticle

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Abstract

Solid O2 has been proposed as a possible reservoir for molecular oxygen in dense clouds through freeze-out processes. The aim of this work is to characterize quantitatively the physical processes that are involved in the desorption kinetics of CO-O2 ices by interpreting laboratory temperature programmed desorption (TPD) data. This information is used to simulate the behavior of CO-O2 ices under astrophysical conditions. The TPD spectra have been recorded under ultra high vacuum conditions for pure, layered and mixed morphologies for different thicknesses, temperatures and mixing ratios. An empirical kinetic model is used to interpret the results and to provide input parameters for astrophysical models. Binding energies are determined for different ice morphologies. Independent of the ice morphology, the desorption of O2 is found to follow 0-order kinetics. Binding energies and temperature-dependent sticking probabilities for CO-CO, O2-O2 and CO-O2 are determined. O2 is slightly less volatile than CO, with a binding energy of versus K for pure ices. In mixed and layered ices, CO does not co-desorb with O2 but its binding energy is slightly increased compared to pure ice whereas that of O2 is slightly decreased. Lower limits to the sticking probabilities of CO and O2 are 0.9 and 0.85, respectively, at temperatures below 20 K. The balance between accretion and desorption is studied for O2 and CO in astrophysically relevant scenarios. Only minor differences are found between the two species, i.e., both desorb between 16 and 18 K in typical environments around young stars. Thus, clouds with significant abundances of gaseous CO are unlikely to have large amounts of solid O2.
LanguageEnglish
Pages1005-1012
Number of pages8
JournalAstronomy and Astrophysics
Volume466
Issue number3
DOIs
Publication statusPublished - May 2007

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desorption
ice
analogs
binding energy
kinetics
temperature
energy
astrophysics
temperature ratio
thickness ratio
mixing ratios
mixing ratio
ultrahigh vacuum
accretion
stars
oxygen

Keywords

  • oxygen
  • interstellar ices
  • astrophysics
  • vacuum
  • kinetics
  • physics
  • astronomy

Cite this

Acharyya, K., Fuchs, G. W., Fraser, H. J., van Dishoeck, E. F., & Linnartz, H. (2007). Desorption of CO and O2 interstellar ice analogs. Astronomy and Astrophysics, 466(3), 1005-1012. https://doi.org/10.1051/0004-6361:20066272
Acharyya, K. ; Fuchs, G.W. ; Fraser, H.J. ; van Dishoeck, E.F. ; Linnartz, H. / Desorption of CO and O2 interstellar ice analogs. In: Astronomy and Astrophysics. 2007 ; Vol. 466, No. 3. pp. 1005-1012.
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Acharyya, K, Fuchs, GW, Fraser, HJ, van Dishoeck, EF & Linnartz, H 2007, 'Desorption of CO and O2 interstellar ice analogs' Astronomy and Astrophysics, vol. 466, no. 3, pp. 1005-1012. https://doi.org/10.1051/0004-6361:20066272

Desorption of CO and O2 interstellar ice analogs. / Acharyya, K.; Fuchs, G.W.; Fraser, H.J.; van Dishoeck, E.F.; Linnartz, H.

In: Astronomy and Astrophysics, Vol. 466, No. 3, 05.2007, p. 1005-1012.

Research output: Contribution to journalArticle

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T1 - Desorption of CO and O2 interstellar ice analogs

AU - Acharyya, K.

AU - Fuchs, G.W.

AU - Fraser, H.J.

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AU - Linnartz, H.

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JO - Astronomy and Astrophysics

T2 - Astronomy and Astrophysics

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Acharyya K, Fuchs GW, Fraser HJ, van Dishoeck EF, Linnartz H. Desorption of CO and O2 interstellar ice analogs. Astronomy and Astrophysics. 2007 May;466(3):1005-1012. https://doi.org/10.1051/0004-6361:20066272