Spectroscopic evidence for interstellar grain clumps in meteoritic inclusions

Abstract

THE occurrence of a primitive, presolar grain component in carbonaceous chondrites has been indicated by several independent lines of evidence, including the discovery of isotopic abundance anomalies^1,2. The occurrence of organic molecules, including amino acids, in these meteorites is also known^3,4, but their connection with a genuinely pre-solar grain component has been conjectural. We show here that an extract of organic material from the Murchison carbonaceous chondrite has an ultraviolet spectrum with an absorption band centred at λ ≈ 2,200 Å. The similarity of this feature with the well-known interstellar absorption band at the same wavelength, gives strong credence to an interstellar grain component within this meteorite.