Non-conservative Mass Transfer in the Neutron Star Stripping Model

The process of long-term 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 a certain point, the stability of the mass transfer is lost, causing the minimum-mass neutron star to explode. In the present stripping calculations, the effect of non-conservative mass transfer has been taken into account for the first time, resulting in 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.