PU-244 IN THE EARLY SOLAR-SYSTEM AND ISOTOPIC ANOMALIES OBSERVED FOR BARIUM, NEODYMIUM AND CARBON IN CARBONACEOUS CHONDRITES

Large isotopic anomalies have recently been discovered in interstellar grains of diamond, graphite and silicon carbide isolated from the car bonaceous chondrites. Re-examination of the existing data for barium a nd neodymium reveals that the anomalous isotopic compositions of these elements observed in the meteorite inclusions can be attributed to th e alterations caused by a combined effect of a) mass-fractionation, b) spallation and c) 10 keV (stellar temperature) neutron-capture reacti ons. Spectacular isotopic anomalies observed in graphite and silicon c arbide grains of the Murchison meteorite can be attributed to the spal lation reactions induced by the high energy protons near the surface o f an exploding supernova.