INTERSTELLAR DIAMONDS IN THE MURCHISON METEORITE - ISOTOPIC CHARACTERIZATION

Interstelllar, microdiamonds, typically 15-30 Angstrom in size, are pr esent in primitive meteorites. The extra-solar origin of these diamond s is confirmed by the presence of isotopic anomalies in nitrogen and x enon. We have successfully isolated microdiamonds from the Murchison m eteorite and confirmed their interstellar origin based on their isotop ic composition. Observation of neon isotopic anomaly characterized by an almost pure Ne-22 component suggests the presence of a small amount of fine-grained interstellar silicon carbide in the analysed sample. Plausible scenarios for the origin of interstellar microdiamond that a re consistent with the isotopic data are presented. The presence of in terstellar microdiamonds in meteorites poses a challenge to the astron omers as direct observational evidence for the presence of diamond in interstellar space is yet to be found.