科研之友
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摘要
We present a model for the formation of silicon carbide aggregates within the expanding and cooling supernova remnant. SiC type-X (SiC-X) grains measured in the laboratory at a high spatial resolution have been found to be aggregates of smaller crystals which are isotopically homogenous. The initial condensation of SiC in the ejecta occurs within an interior dense shell of material which is created by a reverse shock which rebounds from the core-envelope interface. A subsequent reverse shock accelerates the grains forward, but the gas drag from the ejecta on the rapidly moving particles limits their travel distance. By observing the effects of gas drag on the travel distance of grains, we propose that supernova grain aggregates form from material that condensed in a highly localized region, which satisfies the observational evidence of isotopic homogeneity in SiC-X grains.
- 出版日期2009-11-10
