Late formation of silicon carbide in type II supernovae.

Liu, Nan; Nittler, Larry R; Alexander, Conel M O'D; Wang, Jianhua · Sci Adv · 2018

basic_science · Level V

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Abstract

We have found that individual presolar silicon carbide (SiC) dust grains from supernovae show a positive correlation between <sup>49</sup>Ti and <sup>28</sup>Si excesses, which is attributed to the radioactive decay of the short-lived (<i>t</i><sub>½</sub> = 330 days) <sup>49</sup>V to <sup>49</sup>Ti in the inner highly <sup>28</sup>Si-rich Si/S zone. The <sup>49</sup>V-<sup>49</sup>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.