Correlation of 48Ca, 50Ti, and 138La Heterogeneity in the Allende Refractory Inclusions

Hsin-Wei Chen et al.

The Astrophysical Journal Letters,Volume 806, Number 1


Precise determinations of 48Ca anomalies in Allende calcium–aluminum-rich inclusions (CAIs) are reported in this work. There are endemic positive 48Ca/44Ca anomalies in all analyzed CAIs after normalization to 42Ca/44Ca, and it is clearly shown that there is no simple correlation between 48Ca/44Ca and 50Ti/48Ti anomalies, in agreement with Jungck et al. Compared to the 48Ca/44Ca versus 50Ti/48Ti correlation line defined by differentiated meteorites, reported by Chen et al., the CAIs plot to elevated 50Ti/48Ti. Assuming the 48Ca/44Ca anomalies of both CAIs and differentiated meteorites came from the same source, excess 50Ti anomalies in CAIs can be calculated by subtracting the part associated with 48Ca/44Ca. These excesses show a linear correlation with 138La anomalies, a neutrino-process nuclide. According to current stellar nucleosynthetic models, we therefore suggest that the solar system 48Ca, 50Ti, and 138La isotopic variations are made of mixtures between grains condensed from ejecta of neutron-rich accretion-induced SNe Ia and the O/Ne–O/C zone of core-collapse SNe II.