Extremely ${}^{54}$Cr- and ${}^{50}$Ti-rich presolar oxide grains in a primitive meteorite: Formation in rare types of supernovae and implications for the astrophysical context of solar system birth

Larry R. Nittler, Conel M. O'D. Alexander, Nan Liu +1

We report the identification of 19 presolar oxide grains from the Orgueil CI meteorite with substantial enrichments in ${}^{54}$Cr, with ${}^{54}$Cr/${}^{52}$Cr ratios ranging from 1.2 t…