A model study of the thermal evolution of astrophysical ices

M. J. Loeffler, B. D. Teolis, R. A. Baragiola

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

We address the question of the evolution of ices that have been exposed to radiation from stellar sources and cosmic rays. We studied in the laboratory the thermal evolution of a model ice sample: a mixture of water, hydrogen peroxide, dioxygen, and ozone produced by irradiating solid H2O2 with 50 keV H+ at 17 K. The changes in composition and release of volatiles during warming to 200 K were monitored by infrared spectroscopy, mass spectrometry, and microbalance techniques. We find evidence for voids in the water component from the infrared bands due to dangling H bonds. The absorption from these bands increases during heating and can be observed at temperatures as high as ∼155 K. More O2 is stored in the radiolyzed film than can be retained by codeposition of O2 and H2O. This O 2 remains trapped until ∼155 K, where it desorbs in an outburst as water ice crystallizes. Warming of the ice also drastically decreases the intrinsic absorbance of O2 by annealing defects in the ice. We also observe loss of O3 in two stages during heating, which correlates with desorption and possibly chemical reactions with radicals stored in the ice, triggered by the temperature increase.

Original languageEnglish (US)
Pages (from-to)L103-L106
JournalAstrophysical Journal
Volume639
Issue number2 II
DOIs
StatePublished - Mar 10 2006
Externally publishedYes

Keywords

  • Comets: general
  • ISM: general
  • Methods: laboratory
  • Planets and satellites: individual (Jupiter)
  • Radiation mechanisms: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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