Publication Type
Journal
Journal Name
Astrophysical Journal. Letters to the Editor
Publication Date
Volume
738
Issue
2
Abstract
Nanodiamond (ND) was the first extrasolar dust phase to be identified in meteorites. However, the 2 nm average size of the NDs precludes isotopic analysis of individual particles, and thus their origin(s) remains controversial. Using electron microscopy with subnanometer resolution, we show that ND separates from the Allende and Murchison meteorites are actually a two-phase mixture of ND and glassy carbon. This phase mixture is likely the product of supernova shock-wave transformation of pre-formed organics in the interstellar medium (ISM). The glassy carbon–ND mixture is also a plausible contributor to the 2175Å extinction feature in the diffuse ISM.