Nucleosynthetic anomaly
A nucleosynthetic anomaly is a small isotopic difference inherited from material made in different stars.
The Solar System formed from a mixture of material made in many stars. If that mixture had been perfectly blended, every meteorite would have identical isotope ratios once effects such as radioactive decay and mass fractionation were corrected. In fact, small differences remain. These are nucleosynthetic anomalies.
They appear in isotopes of chromium, titanium, molybdenum, nickel, calcium, neodymium and others. For example, chromium-54 and titanium-50 are enriched in carbonaceous chondrites relative to Earth and ordinary chondrites. Such variations are typically tiny, measured in parts per ten thousand, but modern mass spectrometers detect them easily.
Anomalies are carried by presolar grains or by early solids that inherited distinctive mixtures. Because they are not changed by heating or melting, they act as permanent birthmarks, allowing scientists to link meteorites, iron groups and planets to the reservoirs from which they formed and to test models of how Earth and Mars were assembled.
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