Abstract
We describe the analytical techniques developed for the precise measurement of the titanium isotope abundances using a TiO + ion beam. Terrestrial, lunar, and bulk meteorite samples yield identical results. Using a normalization to 46Ti 48Ti for mass dependent isotope fractionation, we obtain the normal Ti composition: 46Ti 48Ti = 0.108548 ; 47Ti 48Ti = 0.099315 ± 0.000005 ; 49Ti 48Ti = 0.074463 ± 0.000004 ; 50Ti 48Ti = 0.072418 ± 0.000004 (2σ grand mean), taking 18O 16O = 0.002045 and 17O 16O = 0.00037 . Measurements on thirteen coarse-grained and fine-grained Ca-Al-Ti-rich inclusions from the Allende and Leoville meteorites show the presence of widespread, significant, nonlinear isotope anomalies in the Ti isotopes which were not used for normalization. The data require the addition of at least three exotic components. The distinct correlation of non-linear effects for the most neutron-rich isotopes of Ca and Ti and the absence of substantial effects at 46Ca in the FUN samples EK-1-4-1 and C-1 indicate that the effects reflect neutron-rich equilibrium or quasi-equilibrium nucleosynthetic processes in the outer layers of a supernova core. The results on Ca and Ti in conjunction with the isotopic effects on other elements (Mg, Sr, Ba, Nd, Sm) show that the samples represent mixtures of different nucleosynthetic components from distinctive processes (‘e’, ‘r’, ‘p’) which do not appear to be related to processes in the same stellar sites.
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