C. M. O'd. Alexander

Presolar components in the ordinary chondrites

Abstract As part of the search for presolar material in primitive meteorites eleven ordinary chondrites, ranging from petrologic type 3 to 6, have been analysed for C and N isotopes by stepped combustion. Isotopically anomalous components have been found only in those meteorites of petrologic type 3.6 or below. In terms of their isotopic composition and combustion temperature these components are similar to, but may not be identical with, those in carbonaceous chondrites. The presence of presolar components in ordinary chondrites may have important implications for the degree of reprocessing their precursor materials can have experienced in the nebula. Although the lack of isotopically anomalous components above type 3.6 may be due to heterogeneous accretion of the ordinary chondrite parent bodies, their destruction during metamorphism provides a more straightforward explanation.