Cosmic ray compaction of porous interstellar ices

U. Raut, M. Famá, M. J. Loeffler, R. A. Baragiola

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

We studied the compaction of microporous vapor-deposited ice films under irradiation with different ions in the 80-400 keV energy range. We found that porosity decreases exponentially with irradiation fluence, with a mean compaction areaper ion that scales linearly with the stopping power of the projectile S above a threshold St = 4 eV Å-1. The experiments roughly follow a universal dependence of ion-induced compaction with restricted dose (eV molecule-1). This behavior can be used to extrapolate our results to conditions of the interstellar medium. Relating our results to ionization rates of interstellar H2, we estimate that porous ice mantles on grains in dense molecular clouds are compacted by cosmic rays in ∼10-50 million years.

Original languageEnglish (US)
Pages (from-to)1070-1074
Number of pages5
JournalAstrophysical Journal
Volume687
Issue number2
DOIs
StatePublished - Nov 10 2008
Externally publishedYes

Keywords

  • Cosmic rays
  • ISM: molecules
  • Methods: laboratory
  • Radiation mechanisms: nonthermal

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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