Cosmic ray compaction of porous interstellar ices

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

doi:10.1086/592193

Cosmic ray compaction of porous interstellar ices

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

Research output: Contribution to journal › Article › peer-review

56 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 S_t = 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 language	English (US)
Pages (from-to)	1070-1074
Number of pages	5
Journal	Astrophysical Journal
Volume	687
Issue number	2
DOIs	https://doi.org/10.1086/592193
State	Published - Nov 10 2008
Externally published	Yes

Keywords

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

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1086/592193

Cite this

@article{91a2b5645f884ce1867c02652dc78d35,

title = "Cosmic ray compaction of porous interstellar ices",

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 {\AA}-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.",

keywords = "Cosmic rays, ISM: molecules, Methods: laboratory, Radiation mechanisms: nonthermal",

author = "U. Raut and M. Fam{\'a} and Loeffler, {M. J.} and Baragiola, {R. A.}",

year = "2008",

month = nov,

day = "10",

doi = "10.1086/592193",

language = "English (US)",

volume = "687",

pages = "1070--1074",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "2",

}

TY - JOUR

T1 - Cosmic ray compaction of porous interstellar ices

AU - Raut, U.

AU - Famá, M.

AU - Loeffler, M. J.

AU - Baragiola, R. A.

PY - 2008/11/10

Y1 - 2008/11/10

N2 - 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.

AB - 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.

KW - Cosmic rays

KW - ISM: molecules

KW - Methods: laboratory

KW - Radiation mechanisms: nonthermal

UR - http://www.scopus.com/inward/record.url?scp=55849151668&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=55849151668&partnerID=8YFLogxK

U2 - 10.1086/592193

DO - 10.1086/592193

M3 - Article

AN - SCOPUS:55849151668

SN - 0004-637X

VL - 687

SP - 1070

EP - 1074

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

ER -

Cosmic ray compaction of porous interstellar ices

Abstract

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Cite this