Galaxies with a minimum in central stellar luminosity density . ... NGC 3706 harbors a high surface brightness ring of starlight with a radius of approximately 20 pc. ... The five other galaxies resemble the endpoints of some simulations of the merging of two gas-free stellar systems, each harboring a massive nuclear black hole. In one version of this scenario, diffuse stellar tori are produced when stars initially bound to one black hole are tidally stripped away by the second black hole. ...