Xenon isotope record of nucleosynthesis and the early solar system

Abstract

ISOTOPIC abundances of Xe were determined as two FeS separates of the Allende (C3V) carbonaceous chondrite were heated, stepwise. A tracer Xe isotope was first produced in one sarnple by 13"Te( n, y 2P) 131rxe reaction to monitor the degassing of Xe from the sample. The FeS melted at 950"C, releasing a spike of 13"xe and terrestrial-type Xe, Xe-T. This confirms that trapped Xe in Allende's FeS is indeed Xe-T, which is also in the atmospheres of the earth and Mars, in the sun, and in FeS of diverse meteorites'" 2 1 . These results imply that Xe-T was in the central, Fe, S-rich region of the protoplanetary nebula, and challenge the main