We present the first post‐core‐collapse models of initially rotating star clusters, using the numerical solution of an orbit‐averaged 2D Fokker–Planck equation. Based on the code developed by Einsel & Spurzem, we have improved the speed and the stability and included the steady three‐body binary heating source. We have confirmed that rotating clusters, whether they are in a tidal field or not, evolve significantly faster than non‐rotating ones. Consequences for the observed shapes, density distribution and kinematic properties of young and old star clusters are discussed. The results are compared with gaseous and 1D Fokker–Planck models in the non‐rotating case.

On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ∼40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ∼2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the time of the second supernova (SN). We generate simulated progenitor populations and follow the three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick velocity. Though not considerably tight, we find these constraints to be comparable to those for Galactic BNS progenitors. The derived constraints are very strongly influenced by the requirement of keeping the binary bound after the second SN and having the merger occur relatively close to the center of the galaxy. These constraints are insensitive to the galaxy's star formation history, provided the stellar populations are older than 1 Gyr.