Late formation of silicon carbide in type II supernovae

We have found that individual presolar silicon carbide (SiC) dust grains from supernovae show a positive correlation between (49)Ti and (28)Si excesses, which is attributed to the radioactive decay of the short-lived (t(½) = 330 days) (49)V to (49)Ti in the inner highly (28)Si-rich Si/S zone. The (49)V-(49)Ti chronometer shows that these supernova SiC dust grains formed at least 2 years after their parent stars exploded. This result supports recent dust condensation calculations that predict a delayed formation of carbonaceous and SiC grains in supernovae. The astronomical observation of continuous buildup of dust in supernovae over several years can, therefore, be interpreted as a growing addition of C-rich dust to the dust reservoir in supernovae.