The effect of heavy cosmic-ray ions on silicate grains in the interstellar dust

G. Szenes, V. K. Kovcs, B. Pécz, V. Skuratov

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Electronmicroscopic samples of crystalline Mg2SiO4 forsterite were irradiated by energetic Ar, Fe, Kr, and Xe ions at room temperature. Tracks with a mean radius Re = 1.36 nm were observed after irradiation by 56MeV Fe ions, while no tracks were induced by a 48MeV Ar beam. Amorphization of forsterite grains by cosmic-ray (CR) Fe ions are discussed, including the effects of low temperature, ion velocity, and ion-induced crystallization. CR Fe ions induce amorphous tracks in crystalline forsterite only in the range 40-140MeV, and the period of time for complete amorphization is τcr ≈ 13,400 Myr. Our estimate is τcr ≈ 1300 Myr for enstatite. Thus, heavy CR particles do not reduce the crystallinity of silicate grains within a reasonable time, as supposed previously. However, energetic ions can induce crystallization in amorphous solids, and this may be partially or fully responsible for the estimated 0.2% crystallinity of silicates in the interstellar medium.

Original languageEnglish
Pages (from-to)288-292
Number of pages5
JournalAstrophysical Journal
Volume708
Issue number1
DOIs
Publication statusPublished - Jan 1 2010

Keywords

  • Cosmic rays
  • Dust, extinction

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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