Nanoscale highly refractory metal alloys in primitive meteorites: condensation processes in the early solar system

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Carbonaceous meteorites contain material that formed in the earliest phases of solar system history. Its investigation contributes to answering questions from astrophysics and geosciences, a key aspect being the origin of the first solids. Calculations predict the most refractory metals to be the first to condense from a cooling gas of solar composition. Primitive meteorites contain these elements as rare refractory metal nuggets (RMN), alloys of metals with low vapor pressure. During preliminary work (funded by DFG, SCHO 341/10- 1) we have found direct evidence for a condensation origin of RMN and have estimated the cooling rate of the gaseous environment from which the first solids formed. Our previous studies were based on chemically separated particles. The aim of the proposed project is the in situ identification of RMN in thin sections followed by analysis of chemical and morphological properties with atomic resolution using transmission electron microscopy. The investigations may enable us to achieve more detailed knowledge concerning the evolution of the gaseous reservoir from which these first solids formed.