Viscous effects on the interaction between the coplanar decretion disc and the neutron star in Be/X-ray binaries

摘要: We study the viscous effects on interaction between coplanar Be-star disc and neutron star in Be/X-ray binaries, using a three-dimensional, smoothed particle hydrodynamics code. For simplicity, we assume Be to be isothermal at temperature of half stellar effective temperature. In order mimic gas ejection process from star, inject particles with Keplerian rotation velocity radius just outside star. Both are treated as point masses. find that is effectively truncated if Shakura‐Sunyaev viscosity parameter αSS � 1, which confirms previous semi-analytical result. disc, material decreted accumulates, so becomes denser more rapidly than around an isolated The resonant truncation results significant reduction amount captured by strong dependence mass-capture rate orbital phase. also eccentric mode excited through direct driving result one-armed bar potential binary. strength greater case smaller viscosity. high-resolution simulation = 0.1, found precess prograde sense. modulates precesses.