An Update on Binary Formation by Rotational Fission

Abstract

During the 1980s, numerical simulations showed that dynamic growth of a barlike mode in initially axisymmetric, equilibrium protostars does not lead to prompt binary formation, i.e. , fission. Instead, such evolutions usually produce a dynamically stable, spinning barlike configuration. In recent years, this result has been confirmed by numerous groups using a variety of different hydrodynamical tools, and stability analyses have convincingly shown that fission does not occur in such systems because gravitational torques cause nonlinear saturation of the mode amplitude. Other possible routes to fission have been much less well scrutinized because they rely upon a detailed understanding of the structure and stability of initially nonaxisymmetric structures and/or evolutions that are driven by secular, rather than dynamic processes. Efforts are underway to examine these other fission scenarios.