The distribution of cosmic-ray-produced rare gases in iron meteorites

1960 ◽  
Vol 65 (9) ◽  
pp. 2947-2964 ◽  
Author(s):  
P. Signer ◽  
A. O. Nier
Keyword(s):  
Cosmic Ray ◽  
Rare Gases ◽  
Iron Meteorites

Helium- und Neonisotope in Eisenmeteoriten

1964 ◽  
Vol 19 (2) ◽  
pp. 210-218 ◽  
Author(s):  
H. Hintenberger ◽  
H. Wanke
Keyword(s):  
Cosmic Ray ◽  
The Sun ◽  
Rare Gases ◽  
Iron Meteorites ◽  
Isotopic Compositions

The helium and neon content of 22 iron meteorites as well as the isotopic compositions of the rare gases have been measured. Definite relations were found between the amounts of the cosmic ray produced isotopes 3He, 4He and 21Ne and also for their ratios. A rough correlation between the mass of the meteorite and the “depth” of the sample has been found; a correlation for the 3He/4He and the 4He/21Ne ratios also exists. The following relationship holds for 19 of the 21 meteorites :3He/4He= 0.166 + 174 (∑ Ne/∑ He) ± 0.018 .The only exceptions are the meteorites Braunau and Colomera. Because these exceptions only show up in diagrams in which the values for 3He are included, we assume that both these meteorites, as well as perhaps also the meteorite Morradal, have lost part of their 3He. This might be explained by a diffusive loss of tritium during times of higher temperatures of the meteoritic bodies, probably due to a closer approach of these meteorites to the sun.

scholarly journals Tritium and Argon-39 in Stone and Iron Meteorites

1969 ◽  
Vol 24 (2) ◽  
pp. 234-244 ◽  
Author(s):  
St. Charalambus ◽  
K. Goebel ◽  
W. Stötzel-Riezler
Keyword(s):  
Cosmic Ray ◽  
Decay Rates ◽  
Earth Atmosphere ◽  
Iron Meteorites ◽  
Production Rates ◽  
Cosmic Ray Intensity ◽  
The Earth ◽  
Cosmic Ray Flux

Tritium and argon-39 measurements of stone and iron meteorites are reported and discussed. The tritium values of stone meteorites are in general higher than those found in other laboratories. The tritium decay rates in irons were low but a relatively high tritium value was measured in the rim of the meteorites. Factors which may influence the production rates are discussed and it is concluded that the average cosmic-ray flux which irradiated the meteorites must be at least a factor of two higher than the values reported by MacDonald for the cosmic-ray intensity at the top of the earth atmosphere.

scholarly journals 3. Fragmentation of Asteroids and Delivery of Fragments to Earth

1977 ◽  
Vol 39 ◽  
pp. 283-291 ◽  
Author(s):  
G. W. Wetherill
Keyword(s):  
Cosmic Ray ◽  
Asteroid Belt ◽  
Combined Effects ◽  
Iron Meteorites ◽  
Exposure Age ◽  
Impact Rate ◽  
Dynamical Time ◽  
Spectrophotometric Data ◽  
Exposure Ages ◽  
Cosmic Ray Exposure Ages

Earth-impacting meteoroids are derived from both comets and asteroids, and some uncertainty still exists regarding with which of these bodies some stone meteorites should be identified. In contrast, the long cosmic ray exposure ages of iron meteorites strongly suggest a long-lived asteroidal source capable of providing ~108 g/yr of this material to the earth’s surface over at least much of solar system history. Spectrophotometric data show that differentiated asteroids are concentrated in the inner portion of the asteroid belt. The orbital histories of fragments of inner belt asteroids are investigated, considering the combined effects of close planetary encounters, secular perturbations, and secular resonances. Particular attention is given to the low inclination (<15°) objects with small semimajcr axis (2.1 to 2.6 A.U.), which can make fairly close approaches to Mars (<0.1 A.U.). It is found that the annual yield and dynamical lifetime of collision fragments of these asteroids is in agreement with the observed impact rate and exposure age of iron meteorites. A smaller yield of stone meteorites (-107 g/yr) is expected, because elimination of these objects by collision is probable on the long dynamical time scaTe. Achondrites could be produced in this way; the yield is probably too low to account for chondrites. Chondrites could possibly be derived indirectly from these bodies insofar as these asteroids are also sources of Apollo and Amor objects.

Determination of Cosmic-Ray-Produced Titanium and. Vahadium in Iron Meteorites.

1968 ◽  
Vol 16 (4) ◽  
pp. 291-302
Author(s):  
MINEO IMAMURA ◽  
MASAKO SHIMA ◽  
MASATAKE HONDA
Keyword(s):  
Cosmic Ray ◽  
Iron Meteorites

Mineralogical and chemical composition and cosmic-ray exposure history of two mesosiderites and two iron meteorites

2000 ◽  
Vol 35 (3) ◽  
pp. 617-628 ◽  
Author(s):  
Dario TERRIBILINI ◽  
Otto EUGSTER ◽  
David W. MITTLEFEHLDT ◽  
Larryn W. DIAMOND ◽  
Stephan VOGT ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Cosmic Ray ◽  
Iron Meteorites ◽  
History Of ◽  
Exposure History
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