Jack Nibbs

Disc construction through common envelope evolution

The common envelope phase of binary stellar evolution is a crucial part of explaining many phenomena, from x-ray binaries, luminous red novae, and short period binaries. All classic post-common envelope binaries have very short orbital periods, a feature that is relatively well understood within the framework of the CE inspiral. On the other hand, a class of post-red and asymptotic giant branch systems (post-RGB and post-AGB) appear to have wider separations, but also small enough that a common envelope interaction must have taken place. These systems always have a large, low mass circumbinary disk. I present scenarios to form large, circumbinary disks that form either as fallback of material that remains bound to the binary after the a CE interaction, or that are created by a weaker, ‘glancing’, interaction. My research explores the regime that must exist between a classical common envelope with its extreme in-spiral and a `glancing’ common envelope with a reduced in-spiral, by using 3D hydrodynamic simulations of both discs and the common envelope phase itself, as a two-pronged approach, to probe this intermediate regime and explain post-RGB and AGB binaries and related objects such as barium stars, CEMP stars and other post-interaction objects.