Refractory Phases in Primitive Meteorites Devoid of [TSUP]26[/TSUP]A[CLC]l[/CLC] and [TSUP]41[/TSUP]C[CLC]a[/CLC]:Representative Samples of First Solar System Solids?

A large number of Ca-Al-rich refractory inclusions in primitive meteorites incorporated the short-lived nuclide 26Al at the time of their formation with an initial 26Al/27Al ratio of 5×10−5. However, there exist inclusions and refractory phases like corundum and hibonite in these meteorites that have no evidence of 26Al. A suite of refractory inclusions from these meteorites also have well-defined initial 26Al/27Al ratios that are lower by factors of 5-1000 compared to the canonical value of 5×10−5. Refractory phases free of 26Al are also devoid of the short-lived nuclide,41Ca. Heterogeneous distribution of the short-lived nuclides in the early solar system and possible formation of refractory inclusions from large clumps of interstellar matter devoid of 26Al are among the suggestions made to explain these observations. In this Letter, we suggest that the refractory phases devoid of 26Al and 41Ca represent some of the first solar system solids that formed in the inner region of the solar nebula prior to the injection of these freshly synthesized nuclides from a stellar source into this region.