Landau

Landau's idea: “normal” stars like the Sun might possess neutron stars at their centers—neutron cores Landau called them.

The reasoning behind Landau’s idea was this: The Sun and other normal stars support themselves against the crush of their own gravity by means of thermal (heat-induced) pressure. As the Sun radiates heat and light into space, it must cool, contract, and die in about 30 million years’ time—unless it has some way to replenish the heat that it loses. Since there was compelling geological evidence, in the 1920s and 1930s, that the Earth had been kept at roughly constant temperature for 1 billion years or longer, the Sun must be replenishing its heat somehow