Two galaxies collide — watch tidal tails form and halos merge
Each "star" orbits two massive central bodies (black holes) using a softened gravitational potential Φ = -GM/√(r²+ε²). The central masses dominate — stellar self-gravity is ignored. This approximation captures the dramatic tidal tail formation and eventual merger seen in real collisions like the Antennae Galaxies (NGC 4038/4039).