Gabriele Cescutti (INAF)

Since the gravitational signal GW170817, it was proved that neutron star mergers produce neutron-capture elements, but we do not know if they are the only producers. At present, we also do not have a clear understanding of the composition of the ejecta and the rate of these events. The answer to these questions is encrypted in the fossil records provided by the abundance pattern of ancient stars in our Galaxy. Using these observations coupled with chemical evolution models, we present how we can improve the constraints on the nature of the first sources of neutron-capture elements, the r-process events, and the first massive stars. Our findings support a scenario where at least a fraction of r-process events has exploded in a very short timescale, and the massive stars at low metallicity were able to produce s-process material.

Presentation (pdf)