THE EFFECT OF HEAVY COSMIC-RAY IONS ON SILICATE GRAINS IN THE INTERSTELLAR DUST

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/708/1/288· OSTI ID:21392485

Szenes, G ^[1]; Kovacs, V K; Pecz, B ^[2]; Skuratov, V ^[3]

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1. Department of Materials Physics, Eoetvoes University, P.O. Box 32, H-1518 Budapest (Hungary)
2. Research Institute for Technical Physics and Materials Science, H-1525 Budapest, P.O. Box 49 (Hungary)
3. Flerov Laboratory of Nuclear Reactions, JINR, 141980 Dubna (Russian Federation)

Electronmicroscopic samples of crystalline Mg{sub 2}SiO{sub 4} forsterite were irradiated by energetic Ar, Fe, Kr, and Xe ions at room temperature. Tracks with a mean radius R{sub e} = 1.36 nm were observed after irradiation by 56 MeV Fe ions, while no tracks were induced by a 48 MeV 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 40-140 MeV, and the period of time for complete amorphization is tau{sub cr} approx 13,400 Myr. Our estimate is tau{sub cr} approx 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.

• OSTI ID: 21392485
• Journal Information: Astrophysical Journal, Vol. 708, Issue 1; Other Information: DOI: 10.1088/0004-637X/708/1/288; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AMORPHOUS STATE
ARGON IONS
COSMIC RADIATION
CRYSTALLIZATION
DUSTS
ENSTATITE
IRON IONS
KRYPTON IONS
MEV RANGE 100-1000
MEV RANGE 10-100
PARTICLE TRACKS
SILICATES
TAIL IONS
TEMPERATURE RANGE 0273-0400 K
XENON IONS
CHARGED PARTICLES
ENERGY RANGE
IONIZING RADIATIONS
IONS
MEV RANGE
MINERALS
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RADIATIONS
SILICATE MINERALS
SILICON COMPOUNDS
TEMPERATURE RANGE