Evidence for the presence of 53Mn in the early solar system

Chromium isotopic anomalies appear to be widespread in the Allende inclusions. Clear anomalies are shown in the 53Cr/52Cr isotopic ratio. Deviations from the terrestrial value are correlated with the Mn/Cr ratios indicating that 53Mn (half life T=3.7 × 106y) existed at the time of formation of the meteorite inclusions. The initial 53Cr/52Cr in the inclusions is lower than the terrestrial value. Recent results have shown that chromium isotopic anomalies are frequent on the 54Cr isotope (Birck and Allègre, 1984). At the same time our results suggested the possibility of some anomalies on the 53Cr isotope which can be produced by the decay of 53Mn. The present article presents improved precision measurements on the same inclusions of the Allende meteorite and an extension of the measurements to mineral separates. These results are the first evidence for live 53Mn in the early solar system (noted 53Mn* in the following).