Speaker
Description
Thorne-Żytkow Objects (TŻOs) are a class of hybrid stars, originally proposed by Thorne & Żytkow (1977), consisting of a neutron star core, surrounded by a diffuse, convective, giant envelope. Recent work by Farmer et al. (2023) to produce models of TŻOs in MESA has reignited interest in structures of these objects.
All plausible formation mechanisms for TŻOs involve a binary interaction, and the mechanism preferred from both the standpoint of population synthesis studies, as well as hydrodynamical simulations involved a CEE event. The effective TŻO formation rate remains an open question, but if even a modest proportion of these binary systems form TŻO, then the population of TŻOs in the Galaxy could be expected to have a significant effect on Galactic Chemical Evolution.
We place central boundary conditions directly at the surface of the neutron star and make use of an Eddington accretion prescription, set by the opacity at the base of the convective envelope to self-consistently model the release of gravitational potential energy, as well as to model to entire radiative region, or "halo" of the Thorne-Żytkow Object.
We discuss our solutions and the implications of the possible existence a parallel series of equilibrium structures for TŻOs. We also discuss the important implications of our structure solutions for possible nucleosynthetic pathways in our models, and the further effects of this on yields of these post-XRB systems, and on Galactic Chemical Evolution as a whole.
