Publication Date



Lunar and Planetary Science Conference XXXI


The molybdenum isotopes in two silicon carbide X grains have been studied with resonant-ionization mass spectrometry (1). The resulting isotopic patterns are anomalous and quite puzzling. In particular, the grains show large excesses in 95Mo and 97Mo. Such an isotopic signature is distinctly different from the s-process pattern seen in the mainstream SiC grains in which 96Mo and 98Mo excesses pre-vail. It is also different from the expected r-process pattern for which the largest expected excess would be at 100Mo. The X grain Mo isotopic patterns suggest a different origin for these isotopes than the classical s- and r-processes.