Mitchell Institute for Fundamental Physics & Astronomy
College Station, Texas 77843
A dynamic and crucial phase in the evolution of a binary star system comes when one star engulfs its companion in a shared gaseous envelope. The two stellar cores spiral tighter in response to drag forces and develop differential rotational with respect to the surrounding envelope gas. Eventually, they may deposit enough energy and momentum to expel the envelope, leaving behind a binary transformed by orbital tightening and mass accretion. In other cases, the objects merge. In this talk, I will share recent results and propose steps toward unwrapping the mystery of this critical phase of binary evolution through a combination of hydrodynamic modeling and new observational constraints.