The Collapse of Solid White Dwarfs

Abstract

We present a model to explain the origin of galactic bulge X-ray sources. We study the evolution of initially cold and massive carbon-oxygen white dwarfs in a close binary system. Under this assumption the core of the white dwarf is solid when the star is reactivated by mass transfer. This implies a low velocity burning front as compared with the fluid case and perhaps a chemical differentiation of the star. Both effects allow the electron captures to overcome the thermonuclear burning. So, the collapse to a neutron star is a very likely outcome.