Nanoanalysis of Presolar Grains

Presolar Grains from Novae

We report the discovery of five SiC grains and one graphite grain isolated from the Murchison carbonaceous meteorite whose major-element isotopic compositions indicate an origin in nova explosions. The grains are characterized by low C/C (4-9) and N/N (5-20) ratios, large excesses in Si (Si/Si ratios range to 2.1 times solar) and high Al/Al ratios. These isotopic signatures are theoretically pr...

PRESOLAR SiC GRAINS OF TYPE C

Presolar Grains from the Qingzhen (eh3) Meteorite

A 28 g sample of the Qingzhen enstatite (EH3) chondrite was subjected to chemical and physical separation procedures to yield several grain-size residues. Ion mapping of isotopes of Si, O, and C in the ion microprobe of two size fractions (QZR4: 0.4–0.8 lm; QZR5: 0.8–2 lm) identified 55 30Si-depleted candidates out of 37,917 Si-rich grains and six 18O-depleted grains out of 54,410 oxides. Subse...

Iron Implantation in Presolar Supernova Grains

We consider the potential of measured iron isotopic ratios within presolar grains from supernovae (as discovered in meteorites) for identifying the gas from which the grains condensed. We show that although iron isotopic ratios vary dramatically with radial coordinate in the initial supernova, it seems likely that the concentration of iron that thermally condenses in SiC grains within the super...

Presolar Grains from Primitive Ordinary Chondrites

Kobayashi, K. Nagashima, N. Sakamoto, S. S. Russell, S. Itoh and H. Yurimoto. Division of Earth and Planetary Sciences, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan ([email protected]); Hawai’i Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, University of Hawai’i at Manoa, Honolulu, HI 96822, USA; Department of Mineralogy, The Natura...