Speaker
Description
Majority of stars in the Universe exist in gravitationally bound binaries and hierarchical multiple systems. Interactions in binary star systems, such as transfer of mass between components, mergers, and explosions, significantly alter stellar evolutionary pathways. The resulting systems can range from mundane to exotic and include gravitational-wave sources and a variety of astrophysical brightenings including cosmologically relevant Type Ia supernovae.
The key phases of single and binary star evolution are often not directly observable and too complex for analytic treatment, necessitating numerical work. We review results from our group at the Institute of Theoretical Physics, Charles University, obtained with multidimensional hydrodynamic, magnetohydrodynamic, and radiation-hydrodynamic simulations using codes developed with the help of ERC Starting Grant and computation time generously allocated at IT4I.
First, we developed a radiation module for the moving-mesh code JET. It is based on mixed-frame grey flux-limited diffusion with implicit time integration. Second, we performed 3D hydrodynamic and magnetohydrodynamic adaptively and statically refined simulations on spherical and Cartesian meshes of the post-dynamical inspiral phase of common envelope evolution. Third, our 3D smoothed particle hydrodynamics simulations showed that a companion grazing a red supergiant on an eccentric orbit can eject envelope material.
We conclude with the computational challenges ahead and our plans for GPU-accelerated codes built around binary-star geometry within our ongoing ERC Consolidator Grant.