A wide variety of exciting astrophysical phenomena involve a pair of stars orbiting each other, often exchanging or sharing material and sometimes merging to form a single object. Regardless of their initial or final state, these systems pass through a phase in which both objects orbit within the same "common envelope", through which they exchange and share material. Complex computer simulations of this phenomenon are perhaps the only way to account for all of the factors that determine the ultimate fate of such a system. The PI and his collaborators will carry out such simulations, which are made possible by the development of terascale and petascale computing technology and investments by NSF in high-performance computing infrastructure. They will use software developed as part of this project to enhance undergraduate astronomy education by creating interactive binary star simulation modules for an online Digital Demo Room site and for a new course in computational astrophysics. Students will be involved both in the research and in developing education materials.
The team will carry out computer simulations to study the physics of common envelopes, a short-lived but crucial phase in the life of close binary stars that may lead to a wide variety of astrophysical phenomena, including certain types of supernovae, gamma-ray bursts, and mergers between stars or black holes. This phase is inherently three-dimensional and cannot be studied using the one-dimensional simulations that underlie our understanding of single-star evolution. They will focus on understanding the sources of energy a common-envelope binary can draw upon in ejecting the outer atmosphere of the larger star and on predicting the appearance of the phase in cases in which the two stars merge together.
