COSMIC RAY COMPACTION OF POROUS INTERSTELLAR ICES

被引：59

作者：

Raut, U. ^{[1
]}

Fama, M. ^{[1
]}

Loeffler, M. J. ^{[1
]}

Baragiola, R. A. ^{[1
]}

机构：

[1] Univ Virginia, Lab Atom & Surface Phys, Charlottesville, VA 22904 USA

来源：

ASTROPHYSICAL JOURNAL | 2008年 / 687卷 / 02期

基金：

美国国家科学基金会;

关键词：

cosmic rays; ISM: molecules; methods: laboratory; radiation mechanisms: nonthermal;

D O I：

10.1086/592193

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

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 area per ion that scales linearly with the stopping power of the projectile S above a threshold S-t = 4eV angstrom(-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 H-2, we estimate that porous ice mantles on grains in dense molecular clouds are compacted by cosmic rays in similar to 10-50 million years.

引用

页码：1070 / 1074

页数：5

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