Double-core evolution. II - Two-dimensional hydrodynamic effects

The evolution of a double-core configuration consisting of a 16 solar mass supergiant and an immersed 1 solar mass neutron star is investigated with a two-dimensional numerical hydrodynamic calculation. When the orbiting neutron star is deep within the envelope, the frictional effects deposit energy rapidly enough to drive a hydrodynamic expansion that is preferentially directed in the equatorial plane. A calculation which follows the expanding material to the surface of the supergiant shows that about 1 solar mass of material is accelerated to escape velocity and suggests that ejection of the entire supergiant envelope could occur. The two-dimensional calculations are compared with previous one-dimensional calculations of double-core evolution.