Stable end-point stars currently fall into two distinct classes — white dwarfs and neutron stars — differing enormously in central density and radial size. No stable cold dead stars are thought to span the intervening densities or have masses beyond ~2–3 solar masses. I show, however, that the general-relativistic condition of hydrostatic equilibrium augmented by the equation of state of a neutron condensate at 0 K generates stable sequences of cold stars that span the density gap and can have masses well beyond prevailing limits. The radial sizes and mass limit of each sequence are determined by the mass and scattering length of the composite bosons. Solutions for hypothetical bosons of ultrasmall mass and large scattering length yield huge self-gravitating systems of low density, resembling galactic dark matter halos.
International Journal of Modern Physics D