When a black hole (black sphere) and a neutron star (red sphere) merge, matter is ejected and forms an accretion disk surrounding the resulting black hole. The simulation shows the density of the ejected matter with colors ranging from blue (lower density), green, yellow to red (higher density).

Rest-mass density in units of g=cm³, temperature (kT) in units of MeV, specific entropy per baryon in units of k, and electron fraction Y_e for model K8. The rest-mass density, the value of Y_e, and the temperature of the  atmosphere artificially added are ≈10 g=cm³, 0.5, and ≈0.036 MeV=k, respectively.