Evolution of a ﹩16\;{{\rm{M}}}_{\odot }+14\;{{\rm{M}}}_{\odot }﹩ system with a 3 day initial orbital period. MESAbinary models are compared to the results of Wellstein et al. (2001), which were calculated using the STERN code. The terms primary and secondary are used throughout the evolution to describe the initially more massive and the less massive components, respectively. For each component in the MESAbinary model, squares mark the ZAMS and the depletion of the indicated nuclear fuel in the core.