Durch Spallationsreaktionen und Neutroneneinfang erzeugtes 36Cl in Meteoriten und die prae-atmosphärische Größe von Steinmeteoriten

1965 ◽  
Vol 20 (4) ◽  
pp. 533-540 ◽  
Author(s):  
F. Begemann ◽  
E. Vilcsek
Keyword(s):  
Mass Loss ◽  
Neutron Capture ◽  
Iron Meteorite ◽  
Iron Meteorites ◽  
Significance Level ◽  
Spallation Reactions ◽  
Limits Of Error ◽  
Good Agreement ◽  
Terrestrial Age ◽  
Comparable Size

The 36Cl produced by spallation reactions and neutron capture on 35Cl has been measured separately in three stone meteorites and one iron meteorite.The spallation produced 36Cl activities - given in dpm per kg (Fe+Ni + 10 x Ca) -have been found to be (20.5 ±2) for Abee - Centre, (21.8 ±2) for Abee - Surface, (21.3 -26.2) for Leedey, and ≦ (22 ±10) for Norton County- Surface. They are in good agreement with those found in iron meteorites of comparable size and known terrestrial age.The neutron induced activities in the same samples are (0.21 ±0.2), (0.08 ± 0.17), (1.7 ±1), and ≦ (30 ± 15) dpm/100 mg Cl. In spite of the large uncertainties highly significant conclusions can be drawn from these data regarding the mass loss of the meteorites during approximately the last million years, either by space erosion or due to ablation during the passage through the terrestrial atmosphere. Based on calculations of EBERHARDT, GEISS, and LUTZ the ratio of post-atmospheric to pre-atmospheric radius derived for the three meteorites is Abee: rM/R=0.86 or rΜ/R > 0.7 on the 3 σ significance level, Leedey (meteorite shower): rM/R=0.5, and Norton County: rM/R=0.77 or rM/R > 0.63 (3 σ level).No neutron induced activity could be detected in the iron meteorite Cranbourne (Nr. 4). The total and spallation produced 36Cl of two adjacent samples - although differing in their Cl content by more than a factor of twenty-was the same within the experimental limits of error (4.7 ± 0.2) dpm/kg. The low value is attributed to a high terrestrial age and/or the size of this meteorite. 39Ar could not be detected (< 0.64 dpm/kg. 3 σ level).

Die Produktionsraten von 36Cl und 39Ar in Metall- und Steinphase des Chondriten Leedey

1966 ◽  
Vol 21 (1-2) ◽  
pp. 110-114
Author(s):  
F. Begemann ◽  
E. Vilcsek ◽  
H. Wänke
Keyword(s):  
Cosmic Radiation ◽  
Large Contribution ◽  
Iron Meteorites ◽  
Production Rates ◽  
Good Agreement ◽  
Comparable Size

The production rates of 36Cl and 39Ar by the cosmic radiation on Fe and Ca +K have been determined in the chondrite Leedey. The values of19.4 atoms/min · kg ≦ PFe (36Cl) ≦ 26.6 atoms/min · kg and PFe (39Ar) = (23.6 ± 1.8) atoms/min · kg are in good agreement with those found in iron meteorites of comparable size. A large contribution of Ca+K to the production of both isotopes is indicated by the ratios9.2 ≦ PCa + K (36Cl) /PFe (36Cl) ≦ 13.6 and PCa + K (39Ar) /PFe (39Ar) = 12.1 ± 1.6. The bearing of these results on the interpretation of 39Ar-data obtained on other chondrites is being discussed.

scholarly journals Dating the Morasko meteorite fall by natural thermoluminescence of the fusion crust

Geologos ◽  
2016 ◽  
Vol 22 (3) ◽  
pp. 251-258 ◽  
Author(s):  
Stanisław Fedorowicz ◽  
Wojciech T. J. Stankowski
Keyword(s):  
Iron Meteorite ◽  
Meteorite Fall ◽  
Local Materials ◽  
Good Agreement

Abstract The date of fall of the Morasko iron meteorite was determined by means of thermoluminescence measurements of the fusion crust and related local materials. Three small pieces, commonly referred to as ‘shrapnel’, were used. The results obtained are 4.5-5.0 ka, which is in good agreement with previous estimates of 4-6 ka on the basis of radiometric, do-simetric and palynological methods.

scholarly journals ISOCAM and DENIS Survey of 0.5 square degrees in the Bar of the LMC. Detection of the whole TP-AGB Star Population

1999 ◽  
Vol 191 ◽  
pp. 561-566
Author(s):  
C. Loup ◽  
E. Josselin ◽  
M.-R. Cioni ◽  
H.J. Habing ◽  
J.A.D.L. Blommaert ◽  
...  
Keyword(s):  
Mass Loss ◽  
High Mass ◽  
Evolutionary Models ◽  
Agb Stars ◽  
Complete Sample ◽  
High Mass Loss ◽  
Low Mass ◽  
The One ◽  
Good Agreement ◽  
Loss Rates

We surveyed 0.5 square degrees in the Bar of the LMC with ISOCAM at 4.5 and 12 μm, and with DENIS in the I, J, and Ks bands. Our goal was to build a complete sample of Thermally-Pulsing AGB stars. Here we present the first analysis of 0.14 square degrees. In total we find about 300 TP-AGB stars. Among these TP-AGB stars, 9% are obscured AGB stars (high mass-loss rates); 9 of them were detected by IRAS, and only 1 was previously identified. Their luminosities range from 2 500 to 14 000 L⊙, with a distribution very similar to the one of optical TP-AGB stars (i.e. those with low mass-loss rates). Such a luminosity distribution, as well as the percentage of obscured stars among TP-AGB stars, is in very good agreement with the evolutionary models of Vassiliadis & Wood (1993) if most of the TP-AGB stars that we find have initial masses smaller than 1.5 to 2 M⊙.

Scanning Electron Microscopy And Electron Probe Microanalysis Of Extraterrestrial Materials

1999 ◽  
Vol 5 (S2) ◽  
pp. 2-3
Author(s):  
J. I. Goldstein
Keyword(s):  
Electron Microscopy ◽  
Low Temperatures ◽  
Electron Probe ◽  
Iron Meteorite ◽  
The Moon ◽  
Iron Meteorites ◽  
Slow Cooling ◽  
Electron Probe Microanalyzer ◽  
Extraterrestrial Materials ◽  
Scanning Electron

One of the first samples analyzed by Castaing in his electron probe microanalyzer (EPMA) some 50 years ago was an iron meteorite. The Widmanstatten pattern microstructure of iron meteorites can be observed at very low magnifications ( Fig. 1). These meteorites are ideal samples for microanalysis because of the Ni gradient which extends over 10 to 1000 microns in the parent taenite phase of these Fe-Ni samples (Fig. 3). The Ni gradient is the result of very slow cooling of the iron meteorite, in terms of millions of years, within a parent'asteroid.The scanning electron microscope (SEM) has been used to characterize the microstructure of meteorites, as well as samples from the moon and mars. For example, the microstructure of the dark etching taenite areas (T in Fig. 1) of the Carleton iron meteorite is shown in Fig 2. In this example, precipitates are observed along original martensite laths which form during the cooling of the iron meteorite at low temperatures.

scholarly journals Drift-corrected trends and periodic variations in MIPAS IMK/IAA ozone measurements

2014 ◽  
Vol 14 (5) ◽  
pp. 2571-2589 ◽  
Author(s):  
E. Eckert ◽  
T. von Clarmann ◽  
M. Kiefer ◽  
G. P. Stiller ◽  
S. Lossow ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Recent Literature ◽  
Michelson Interferometer ◽  
Quasi Biennial Oscillation ◽  
Significance Level ◽  
Tropical Tropopause ◽  
Time Period ◽  
Ozone Trends ◽  
Institute Of Technology ◽  
Good Agreement

Abstract. Drifts, trends and periodic variations were calculated from monthly zonally averaged ozone profiles. The ozone profiles were derived from level-1b data of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) by means of the scientific level-2 processor run by the Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK). All trend and drift analyses were performed using a multilinear parametric trend model which includes a linear term, several harmonics with period lengths from 3 to 24 months and the quasi-biennial oscillation (QBO). Drifts at 2-sigma significance level were mainly negative for ozone relative to Aura MLS and Odin OSIRIS and negative or near zero for most of the comparisons to lidar measurements. Lidar stations used here include those at Hohenpeissenberg (47.8° N, 11.0° E), Lauder (45.0° S, 169.7° E), Mauna Loa (19.5° N, 155.6° W), Observatoire Haute Provence (43.9° N, 5.7° E) and Table Mountain (34.4° N, 117.7° W). Drifts against the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) were found to be mostly insignificant. The assessed MIPAS ozone trends cover the time period of July 2002 to April 2012 and range from −0.56 ppmv decade−1 to +0.48 ppmv decade−1 (−0.52 ppmv decade−1 to +0.47 ppmv decade−1 when displayed on pressure coordinates) depending on altitude/pressure and latitude. From the empirical drift analyses we conclude that the real ozone trends might be slightly more positive/less negative than those calculated from the MIPAS data, by conceding the possibility of MIPAS having a very small (approximately within −0.3 ppmv decade−1) negative drift for ozone. This leads to drift-corrected trends of −0.41 ppmv decade−1 to +0.55 ppmv decade−1 (−0.38 ppmv decade−1 to +0.53 ppmv decade−1 when displayed on pressure coordinates) for the time period covered by MIPAS Envisat measurements, with very few negative and large areas of positive trends at mid-latitudes for both hemispheres around and above 30 km (~10 hPa). Negative trends are found in the tropics around 25 and 35 km (~25 and 5 hPa), while an area of positive trends is located right above the tropical tropopause. These findings are in good agreement with the recent literature. Differences of the trends compared with the recent literature could be explained by a possible shift of the subtropical mixing barriers. Results for the altitude–latitude distribution of amplitudes of the quasi-biennial, annual and the semi-annual oscillation are overall in very good agreement with recent findings.

scholarly journals Fe-Ni-P-S Melt Pockets in Elga IIE Iron Meteorite: Evidence for the Origin at High-Pressures Up to 20 GPa

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 616 ◽  
Author(s):  
Konstantin Litasov ◽  
Svetlana Teplyakova ◽  
Anton Shatskiy ◽  
Konstantin Kuper
Keyword(s):  
Experimental Data ◽  
Solid Solution ◽  
Important Implication ◽  
High Pressures ◽  
Bulk Composition ◽  
Parent Body ◽  
Iron Meteorite ◽  
Iron Meteorites ◽  
High Pressures And Temperatures ◽  
Melt Pockets

Here we report new data on high-pressure microstructures in Elga group IIE iron meteorites, made of solidified Fe-Ni-P-S melt pockets and microcrystalline aggregates, which could be formed only at high pressures and temperatures according to the experimental data. The bulk composition of the melt pockets and crystals correspond to the Fe3P-Fe3S solid solution with the closure of an immiscibility gap at pressures near 20 GPa in static experiments. Some other melt pockets fit with the Fe2S-Fe2P compositions, which could also correspond to high pressures and temperatures. The results suggest a late shock episode during the formation of the IIE iron parent body, which may be prior or due to the final disruption that caused the meteorite arrival to Earth. It also has an important implication to the shock features in other meteorites, such as ureilite.

Origin of Iron Meteorite Groups IAB and IIICD

1980 ◽  
Vol 35 (8) ◽  
pp. 781-795 ◽  
Author(s):  
John T. Wasson ◽  
John Willis ◽  
Chien M. Wai ◽  
Alfred Kracher
Keyword(s):  
Parent Body ◽  
Iron Meteorite ◽  
Iron Meteorites ◽  
Impact Melt ◽  
Equilibrium Crystallization ◽  
Ni Content ◽  
Oxide Phases ◽  
Host Metal ◽  
Impact Melts ◽  
The Impact

AbstractSeveral low-Ni iron meteorites previously assigned to group IAB are reclassified IIICD on the basis of lower Ge, Ga, W and Ir concentrations and higher As concentrations; the low-Ni extreme of IIICD is now 62 mg/g, that of IAB is 64 mg/g. The resulting fractionation patterns in the two groups are quite similar. It has long been established that, in contrast to the magmatic iron meteorite groups, IAB and IIICD did not form by fractional crystallization of a metallic magma. Other models have been proposed, but all have serious flaws. A new model is proposed involving the formation of each iron in small pools of impact melt on a parent body consisting of material similar to the chondritic inclusions found in some IAB and IIICD irons, but initially unequilibrated. These impact melts ranged in temperatures from ~ 1190 K to ~ 1350 K. The degree of equilibration between melt and unmelted solids ranged from minimal at the lowest temperature to moderate at the highest temperature. The lowest temperature melts were near the cotectic in the Fe-Ni-S system with Ni contents of ~ 12 atom %. Upon cooling, these precipitated metal having ~ 600 mg/g Ni by equilibrium crystallization. The Ni-rich melt resulted from the melting of Ni-rich sulfides and metal in the unequilibrated chondritic parent. Low-Ni irons formed in high temperature melts near the composition of the FeS-Fe eutectic or somewhat more metal rich. We suggest that the decreasing Ge, Ga and refractory abundances with increasing Ni concentration reflect the trapping of these elements in oxide phases in the unequilibrated chondritic material, and that very little entered the Ni-rich melt parental to the Oktibbeha County iron. The remaining elements tended to have element/Ni ratios in the melts that were more or less independent of temperature. The remarkable correlation between I-Xe age of the chondritic inclusions and Ni content of the host metal is explained by a detailed evolution of (mega)regolith in which these groups originated. The most Ni-rich melts could only be generated from an unequilibrated chondrite parent; as the continuing deposition of impact energy produced increasingly higher grades of metamorphism, the maximum Ni content of the impact melts (and their subsequently precipitated metal) gradually decreased.

scholarly journals 109Ag Nuclear Magnetic Resonance Studies of Organic and Inorganic Silver Complexes

1976 ◽  
Vol 31 (12) ◽  
pp. 1532-1538 ◽  
Author(s):  
K. Jucker ◽  
W. Sahm ◽  
A. Schwenk
Keyword(s):  
Aqueous Solutions ◽  
Chemical Exchange ◽  
Chemical Shifts ◽  
Linear Functions ◽  
Silver Salts ◽  
Two Samples ◽  
Chemical Shift Data ◽  
Limits Of Error ◽  
Ethyl Amine ◽  
Good Agreement

AbstractThe NMR lines of 109Ag have been investigated in solutions of several silver salts in acetonitrile, propionitrile, pyridine, and ethylenediamine, and also in aqueous solutions of Na2S2O3 and ethyl-amine. In these solvents the Ag+ -ions form one or several complexes. In any case a single NMR line was to be detected, i. e. a rapid chemical exchange between different complexes in a sample may be assumed. The concentration dependence of the chemical shifts was determined with high accuracy for these solutions. From these results the chemical shift data of some defined complexes were derived. The chemical shifts of mixtures of AgCl and AgBr and also of AgCl and Agl dissolved in 70% aqueous solution of ethylamine are linear functions of the anions mole fraction. In two samples of AgNO3 dissolved in organic solvents, the ratio υ(109Ag)/υ(107Ag) = 1.149 640 (1) was measured in good agreement with the value from silver salts in aqueous solutions; i. e. no primary isotopic effect was to be detected within these limits of error (0.9 ppm).

Neutron capture on Pt isotopes in iron meteorites and the Hf–W chronology of core formation in planetesimals

2013 ◽  
Vol 361 ◽  
pp. 162-172 ◽  
Author(s):  
Thomas S. Kruijer ◽  
Mario Fischer-Gödde ◽  
Thorsten Kleine ◽  
Peter Sprung ◽  
Ingo Leya ◽  
...  
Keyword(s):  
Neutron Capture ◽  
Core Formation ◽  
Iron Meteorites
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