Publication Date



Lunar and Planetary Science Conference XXXI


Supernovae are profoundly radioactive. Accord-ingly, we seek a new picture for radioactive regulation of the condensation of dust within their comoving, expanding, and cooling gaseous interiors. Such supernova condensates (SUNOCONs 1,2) from presolar galactic supernovae are recovered from meteorites (graphite, SiC) and are identified by predicted (3) excess 26Mg, 41K, and 44Ca from post-event decay of 26Al, 41Ca and 44Ti (4). Their isotopic compositions suggest mixed-shell material. This suggests two puzzles: 1.Why are the discovered SUNOCONs so large? 2.Where are the expected more numerous ones from unmixed super-nova shells? We propose that the large sizes and the miner-alized structures of SUNOCONs result from five controls: population control, cooling, admixed seed grains, catalysis, and entropic arrow. The constraints are driven by radioac-tivity and rapid decline of gas density, which maintains atomic abundances far from thermal equilibrium. Central to the carbide SUNOCONs is the CO molecule, whose disrup-tion by Compton electrons (5) maintains free carbon that enables graphite or SiC growth.