Presolar graphite: Noble gases and their origins

Abstract

Presolar graphite contains a 22Ne-rich component called Ne-E(L). Noble gas studies on graphite aggregates and single grains have shown that although a dominant source of the 22Ne is 22Na, 22Ne in the He-shell of asymptotic giant branch stars have also contributed to the Ne-E(L). In addition to novae that have been considered to be a possible source of 22Na, supernovae are a likely source as well. Krypton isotopic ratios of the separates indicate that part of graphite formed in low-mass (≤3 M⊙) asymptotic giant branch stars of low metallicity (Z ≤ 0.006). © Astronomical Society of Australia 2003.