Interstellar diamonds in the Murchison meteorite: isotopic characterization

Abstract

Interstellar microdiamonds, typically 15-30 Å in size, are present in primitive meteorites. The extrasolar origin of these diamonds is confirmed by the presence of isotopic anomalies in nitrogen and xenon. We have successfully isolated microdiamonds from the Murchison meteorite and confirmed their interstellar origin based on their isotopic composition. Observation of neon isotopic anomaly characterized by an almost pure ²²Ne 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 are consistent with the isotopic daata are presented. The presence of interstellar microdiamonds as direct observational evidence for the presence of diamond in interstellar space is yet to be found.