Non-conservative Mass Transfer in the Neutron Star Stripping Model

The process of long-duration stable mass transfer (or stripping) in a close neutron star binary system is possible at a sufficiently large initial asymmetry of the component masses. At the final stage of the evolution of such systems the low-mass neutron star fills its Roche lobe, whereupon its mass is gradually transferred to the more massive component. At some instant of time the transfer stability is lost, causing the minimum-mass neutron star to explode. In the stripping calculations the effect of non-conservative mass transfer has been taken into account for the first time, leading to an increase in the duration of stable mass transfer from a few tenths of a second to a few seconds. This allows the time delay of 1.7 s between the loss of the gravitational-wave signal and the detection of the gamma-ray burst from the multimessenger event GW170817–GRB170817A to be naturally explained. The interaction of the envelope of the exploded minimum-mass neutron star with the matter ejected during non-conservative mass transfer may explain two episodes in the light curve of this gamma-ray burst.