Stardust In Primitive Solar System Materials.

Primitive meteorites, interplanetary dust particles, and matter from comet Wild 2 returned to Earth by NASA’s Stardust mission contain small quantities of refractory dust grains with highly anomalous isotopic compositions. These grains represent a sample of stardust that can be analyzed in the laboratory for isotopic and chemical composition and mineralogy. Among the identified stardust minerals are silicon carbide, graphite, silicon nitride, oxides, and silicates. Most of these grains apparently formed in the winds of low- and intermediate-mass asymptotic giant branch stars as indicated by CNO isotopic compositions and fingerprints of s-process nucleosynthesis. Some grains are likely to be from Type II supernovae, as indicated by specific isotopic signatures in C, N, O, and Si, and high abundances of radiogenic ²⁶Mg, ⁴¹K, ⁴⁴Ca, and ⁴⁹Ti from the decay of radioactive ²⁶Al, ⁴¹Ca, ⁴⁴Ti, and ⁴⁹V. Rare a grains from novae. [ABSTRACT FROM AUTHOR]