Finding $r$-II sibling stars in the Milky Way with the Greedy Optimistic Clustering algorithm

Kohei Hattori, Akifumi Okuno, Ian U. Roederer

$R$-process enhanced stars with [Eu/Fe]$\ge +0.7$ (so-called $r$-II stars) are believed to have formed in an extremely neutron-rich environment in which a rare astrophysical event…