CONSTRAINTS ON R-PROCESS NUCLEOSYNTHESIS IN ACCRETION DISKS

IT has been suggested 1 that matter in accretion disks around compact objects such as black holes or neutron stars, which appear to be responsible for galactic X-ray sources, may experience ideal conditions for classical rapid neutron-capture ('r-process') nucleosynthesis 2. Systems in which accretion drives an outflow from a region near the compact object might thereby enrich the interstellar medium in r-process elements, such as europium. Here I present a more detailed assessment of the efficacy of this mechanism for the r-process. By considering the constraints imposed by typical accretion-disk conditions, I conclude that r-process elements are unlikely to have been made this way, largely because the total production is too low, by a factor of approximately 10(5), to explain the observed abundances.