Relativistic isentropic stellar models

Relativistic, isentropic, homogeneous models are constructed by a method that automatically detects instabilities, and evolutionary tracks of central conditions are shown on a (T, ρ{variant}) diagram. Models heavier than 20 M_⊙ become unstable because of pair creation. Iron photodisintegration causes instability in the mass range between 1.5 M_⊙ and 20 M_⊙. General relativistic effects bring about the onset of instability in models of 1.2-1.5 M_⊙ when the central density is about 10¹⁰ g/cm³. Lighter models become white dwarfs. It is pointed out that general relativistic instability will prevent the formation of neutron stars through hydrostatic evolution and may be relevant in setting off low-mass supernovae.