English

Constraints on $R$-process Nucleosynthesis from $^{129}$I and $^{247}$Cm in the Early Solar System

Astrophysics of Galaxies 2022-02-16 v2 Solar and Stellar Astrophysics

Abstract

GW170817 has confirmed binary neutron star mergers as one of the sites for rapid neutron capture (rr) process. However, there are large theoretical and experimental uncertainties associated with the resulting nucleosynthesis calculations and additional sites may be needed to explain all the existing observations. In this regard, abundances of short-lived radioactive isotopes (SLRIs) in the early solar system (ESS), that are synthesized exclusively by rr-process, can provide independent clues regarding the nature of rr-process events. In this work, we study the evolution of rr-process SLRIs 129^{129}I and 247^{247}Cm as well as the corresponding reference isotopes 127^{127}I and 235^{235}U at the Solar location. We consider up to three different sources that have distinct 129^{129}I/247^{247}Cm production ratios corresponding to the varied rr-process conditions in different astrophysical scenarios. In contrast to the results found by C\^ot\'e et al. (2021), we find that 129^{129}I and 247^{247}Cm in the ESS do not come entirely from a single major event but get contributions from at least two more minor contributors. This has a dramatic effect on the evolution of the 129^{129}I/247^{247}Cm ratio, such that the measured ESS value in meteorites may not correspond to that of the "lastlast" major rr-process event. Interestingly, however, we find that the 129^{129}I/247^{247}Cm ratio, in combination with the observed 129^{129}I/127^{127}I and 247^{247}Cm/235^{235}U ratio in the ESS, can still provide important constraints on the properties of proposed rr-process sources operating in the Milky Way.

Keywords

Cite

@article{arxiv.2110.05449,
  title  = {Constraints on $R$-process Nucleosynthesis from $^{129}$I and $^{247}$Cm in the Early Solar System},
  author = {Projjwal Banerjee and Meng-Ru Wu and Jeena S. K},
  journal= {arXiv preprint arXiv:2110.05449},
  year   = {2022}
}

Comments

14 pages, 5 figures, 7 tables