On the evolutionary scheme W UMa→CV→Type I SN

Considerations of space densities and lifetimes indicate that W UMa stars evolve into cataclysmic variable stars, and that these later turn into one of the two kinds of Type I supernovae. It is suggested that the mechanism for the latter evolutionary stage is the transfer of helium from the remnant of the secondary to the primary, resulting in pushing the white dwarf primary over the Chandrasekhar limit.