Exploring the Tidal Effects of Close Binaries on Be Star Disks

As the majority of massive stars, Be stars are often members of a binary system. The companion star might be a compact star emitting X-rays, a hot subdwarf O or B star that emits in the UV range or a low-mass main sequence star, which is a case difficult to detect. Whatever the nature of the companion, it interacts in multiple ways with the Be decretion disk: as a source of high energy particles, through radiative interaction, or via tidal interaction. In this work we focus in the study of the tidal effects between the two stars. In the past, a smoothed particle hydrodynamics code has been used to explore the effect of the value of viscosity, assuming that the disk is isothermal and the two stars have co-planar and aligned or slightly misaligned orbits. We are going to use the same smoothed particle hydrodynamics code, in order to explore the evolution of the system more thoroughly, not only expanding to further ranges of the parameter space, but also in the cases of counter-aligned and misaligned orbits. With our simulations we expect to give an insight on the conditions that maximize the tidal interaction, and more specifically the effect of the viscosity parameter, the orbital period, the eccentricity, and the tilt of the stellar rotational axis with respect to the orbital plane.