The evolution of low-mass close binaries influenced by the radiation of gravitational waves and by a magnetic stellar wind

Numerical models are presented for the evolution of low-mass binaries. Stars with 0.79-1.25 solar mass are assumed to fill their Roche lobe, and account is taken of the loss of angular momentum (AM) by emission of gravitational waves and through a stellar magnetic wind. Three evolutionary groups are characterized; the first is dominated by the AM loss mechanisms and has periods under 15 hr; the second group has periods over 15 hr and under 2 yr and features He cores after Roche lobe filling commences; the third group has a common envelope phase and a donor star with a massive degenerate core and a deep convective envelope before filling the Roche lobe. Algol stars are typical of the second group. All scenarios eventually experience exposure of He-3 on the donor. The transfer of He-3 to a degenerate companion results in nova-like explosions on the surface of the dwarf.