  Despite numerous efforts to better understand binary star evolution, some
aspects of it remain poorly constrained. In particular, the evolution of
eccentric binaries has remained elusive mainly because the Roche lobe formalism
derived for circular binaries does not apply. Here, we report the results of
our Smoothed Particle Hydrodynamics simulations of mass transfer in eccentric
binaries using an alternate method in which we model only the outermost layers
of the stars with appropriate boundary conditions. Using this technique, along
with properly relaxed model stars, we characterize the mass transfer episodes
of binaries with various orbital parameters. In particular, we show that these
episodes can be described by Gaussians with a FWMH of ~0.12 P_orb and that the
peak rates occur after periastron, at an orbital phase of ~0.58, independently
of the eccentricity and mass of the stars. The accreted material is observed to
form a rather sparse envelope around either or both stars. Although the fate of
this envelope is not modeled in our simulations, we show that a constant
fraction (~5%) of the material transferred is ejected from the systems. We
discuss this result in terms of the non-conservative mass transfer scenario. We
suggest our results could be incorporated in analytical and binary population
synthesis studies to help better understand the evolution of eccentric binaries
and the formation of exotic stellar populations.
