Supernova: The Result of the Death Spiral of a White Dwarf into a Red Giant

The proposed model is a binary consisting of a white dwarf and a star evolving toward the red-giant branch. Conditions are given under which the revolution period of the binary and the rotation period of the red giant will reach a synchronous state and under which no stable synchronous orbit is possible. For the case of a nonstable synchronous orbit, the evolution of the decay of the orbit is given. It is shown that the white dwarf spirals in toward the red giant, enters the red giant's surface, and drops rapidly toward the core. We suggest that a supernova explosion will result from a collision with the core and leave a neutron stellar remnant. The relationship to binary X-ray stars is discussed. Subject headings: binaries - neutron stars supernovae - white dwarf stars - X-ray sources