340 research outputs found
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Isotopic and Micro-Raman investigation of Interplanetary Dust Particles Collected during 2003 Earth passage through Comet Grigg-Skjellerup Dust Stream
We report microscale H and N isotopic and Raman spectral data for IDPs collected in April 2003. The samples show extreme D and 15N enrichments carried by very primitive organic matter. A high abundance of D anomalies might indicate a cometary origin
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Remarkably high abundance of presolar grains in interplanetary dust particles collected from the comet Grigg-Skjellerup dust stream
Isotopic studies of IDPs collected from the comet Grigg-Skjellerup dust stream reveal extremely high abundances of presolar grains in two of four IDPs. These abundances exceed those of any other extraterrestrial material analyzed and support a cometary origin for these IDPs
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Scanning micro-raman spectroscopy on carbon-rich residues of primitive chondrites: A tool for chondrite classification and stardust analysis
We present results obtained by Raman spectroscopy of various organic residues of primitive chondrites in order to better characterize the microstructural state of the organic matter. These results will be correlated with the petographic classification of the chondrites
Galactic age estimates from O-rich stardust in meteorites
The 16O/17O and 16O/18O ratios of refractory oxide grains extracted from primitive meteorites suggest that they originated in low-mass red giant stars prior to the formation of the Solar System 4.6×109 years ago. Detailed comparison of the isotopic compositions of the grains with models of stellar evolution and galactic chemical evolution imply that the age of the Galaxy is 14.4 Gyr with a statistical error of ±1.3 Gyr. Systematic uncertainties are of order several Gyr, however, and are primarily due to inadequacies in present theoretical modeling
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Extensive microscale N isotopic heterogeneity in chondritic organic matter
Introduction: H and N isotopic anomalies (mainly excesses of D and 15N) in organic matter from primitive meteorites and IDPs suggest preservation of presolar molecular cloud material [1-3]. However, there have been very few spatially correlated H and N studies for either chondrites or IDPs [4, 5]. We report C and N isotopic imaging data for organic matter from four meteorites and three IDPs. D/H imaging data for many of the same samples are presented in [6, 7] and bulk organic isotope data in [8]
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Correlated analytical studies of organic material from the Tagish Lake carbonaceous chondrite
We report on correlated studies of organic material using SIMS, FIB-SEM, and TEM
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Extreme H isotopic anomalies in chondritic organic matter
Extract from introduction: We have conducted ionprobe (IMS6f and NanoSIMS) imaging studies of various samples for H, D, C, 14N and 15N. These will ultimately be correlated with micro-analytic techniques such as FIB/TEM or STXM/XANES. We analyzed matrix fragments from Bells (CM2), Al Rais (CR2) and Tagish Lake (unique) [2], high purity insoluble organic matter (IOM) [3] extracted from EET92042 (“EET”, CR2), Bells, Murchison (CM2), Allende (CV3), Krymka (LL3.1) and, for comparison, 3 IDPs
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Were Presolar Grains Destroyed by the Nebular Process Responsible for the Volatile Element Fractionation?
We present SiC abundances from a number of CM and CR chondrites using NanoSIMS raster ion imaging of acid residues. We find higher SiC abundances for CRs than previously estimated based on noble gases
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