Iron Isotopic Diagnostics of Presolar Supernova Grains

The most thoroughly studied of the isotopi-cally anomalous presolar grains are silicon-carbide crystals (1). Both X-type SiC and low-density graphite grains condensed within the interiors of supernovae during their expansion and cooling (2). This paper concerns itself with iron in those su-pernova condensates (SUNOCONs), for which Fe anomalies was an early prediction (3). A major problem in SUNOCON interpretation has been that although the grains clearly rep-resent supernova interiors, it is not clear from which parcels of gas the grains condensed. The presence of 60-yr Ti in SUNOCONs as a major isotope of Ti demonstrates the prompt condensation of titanium, long before supernova ejecta have mixed with circumstellar matter, and even long before the reverse shock reheats the supernovae ejecta.