Mass transfer instabilities due to angular momentum flows in close binaries

The paper investigates the onset of dynamical mass transfer instabilities due to angular momentum flows in close low-mass binaries. Allowance is made for the finite growth time of the instability. The results are applied to the formation of single millisecond pulsars in the galactic disk and it is found that mass transfer from a white dwarf onto a neutron star is dynamically unstable for white dwarf masses greater than about 0.5 solar masses. This lower limit for unstable mass transfer is somewhat larger than that found previously. A further application is the formation of long period and ultrashort-period white-dwarf/neutron-star binaries, via mass transfer from a giant to a neutron star. It is found that incipient mass transfer from an approximately 0.8-solar mass giant to an approximately 1.2-solar mass neutron star occurs on a sufficiently slow time scale for an accretion disk to form.