Constraining the rapid neutron-capture process with meteoritic 129-I and 247-Cm
B. Côtè, M. Eichler, A. Yague, N. Vassh, M. Mumpower, B. Vilagos, B. Soos, A. Arcones, T. M. Sprouse, R. Surman, M. Pignatari, B. Wehmeyer, T. Rauscher, M. Lugaro
Published Science 371 945-948 (2021)
Meteoritic analysis demonstrates that radioactive nuclei heavier than iron were present in the early Solar System. Among them, 129I and 247 Cm both have a rapid neutron-capture process (r process) origin and decay on the same timescale (15.6 Myr). We show that the 129I/247Cm abundance ratio in the early Solar System (438 ± 184) is immune to galactic evolution uncertainties and represents the first direct observational constraint for the properties of the last r-process event that polluted the pre-solar nebula. We investigate the physical conditions of this event using nucleosynthesis calculations and demonstrate that moderately neutron-rich disk ejecta can produce the observed ratio. We conclude that a dominant contribution by exceedingly neutron-rich ejecta is highly disfavored.