نتایج جستجو برای: meteoritic iron
تعداد نتایج: 143039 فیلتر نتایج به سال:
Fowler, Greenstein, and Hoyle have proposed that the inner solar system was heavily irradiated during its formation. A consequence of this proposal is that sizable differences in meteoritic and terrestrial K'3⁄4K 'ø ratios are possible if the fraction of material which was irradiated was different in the two cases. The isotopic composition of potassium was measured by mass spectrometry for nine...
We report the unusual discovery of a natural iron "glaze" composed of fused particles of meteoritic origin, concentrated entirely within a crop formation in England, appearing shortly after the intense Perseid meteor shower in August, 1993. Physical and chemical characteristics as well as spatial distributions indicated reheating to a semi-molten state at the time of crop impact, suggesting inv...
Abstract The frequency of crater-producing asteroid impacts on Earth is not known. Of the predicted Holocene impact craters <200 m diameter, only ~30% have been located. Until now there has no way to distinguish them from “normal” terrestrial structures unless pieces iron meteorites were found nearby. We show that reflective properties charcoal in proximal ejecta small are distinct those...
[1] Impact craters and the discovery of meteorites on Mars indicate clearly that there is meteoritic material at the Martian surface. The Alpha Particle X-ray Spectrometers (APXS) on board the Mars Exploration Rovers measure the elemental chemistry of Martian samples, enabling an assessment of the magnitude of the meteoritic contribution. Nickel, an element that is greatly enhanced in meteoriti...
Extraterrestrial polymers of glycine with iron have been characterized by mass spectrometry to a core 1494 Da dominant rod-like variants at charge ratios 1567 and 1639 [McGeoch et al., “Meteoritic proteins glycine, lithium,” arXiv:2102.10700 (2021)]. Several principal macro-structural morphologies are observed in solvent extracts from chondritic Vigarano class alteration type 3 meteoritic mater...
Introduction: Data on the Ni concentration and distribution in kamacite (α) and taenite (γ) of meteoritic metal can be used to determine the cooling rates of meteorites. Several metallographic cooling rate methods have been used to determine the cooling rates of meteorites and have been recently reviewed [1]. The reliability of these models depends on the accuracy of the phase diagram and diffu...
The astrophysical origins of ∼3 nm-diameter meteoritic nanodiamonds can be inferred from the ratio of C/ C 12 13 . It is essential to achieve high spatial and mass resolving power and minimize all sources of signal loss in order to obtain statistically significant measurements. We conducted atom-probe tomography on meteoritic nanodiamonds embedded between layers of Pt. We describe sample prepar...
The metal and sulfide phases in the Luna 24 soil samples were studied with the optical microscope and the electron microprobe. The compositions of the metal particles fall into three groups based on their Ni and Co contents: (1) Samples of meteoritic composition which have undergone metamorphism on the lunar surface. (2) Samples of submeteoritic, low Ni and low Co contents, including most of th...
Phosphorylation of the nucleosides adenosine and uridine by the simple mixing and mild heating of aqueous solutions of the organic compounds with synthetic analogs of the meteoritic mineral schreibersite, (Fe,Ni)3P under slightly basic conditions (pH ~9) is reported. These results suggest a potential role for meteoritic phosphorus in the origin and development of early life.
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