Double-Core Evolution. III. The Evolution of a 5 M Red Giant with a 1 M Companion

The two-dimensional hydrodynamical evolution of the double core has been investigated for a configuration consisting of a 1 solar mass main-sequence star and a 5 solar mass red giant in its hydrogen and helium shell-burning stage. The common envelope evolution is followed to the late stages, and it is demonstrated that more than about 3 solar masses can be ejected in an equatorial outflow. This result is insensitive to the binary orbital period immediately prior to the double-core phase. For the chosen parameters, the results were independent of the initial orbital separations and of the form of the energy dissipation rate. It is probable that the entire common envelope will be ejected and that the coalescence of the two cores can be avoided. The mass-loss process is adiabatic, but with an efficiency for conversion of orbital energy into mass ejection ranging between 0.3 and 0.6.