Gabriel Tomassini (Observatoire de la Côte d'Azur): Binarity in Evolved Stars: From VLT/SPHERE Observations to 3D RHD Simulations

Thursday 26 Feb 2026, 14:00 → 15:00 Europe/Stockholm

Å80127

Title:  Binarity in Evolved Stars: From VLT/SPHERE Observations to 3D RHD Simulations
Speaker: Gabriel Tomassini
Affiliation: Observatoire de la Côte d'Azur, France
Room: 80127

Abstract:
Evolved stars are primary engines of chemical enrichment in galaxies, driven by intense mass-loss processes. Understanding the complex structure and dynamics of their extended atmospheres is essential to constraining this enrichment; yet, stellar models frequently omit a crucial factor: binarity.

Despite the fact that a large fraction of stars exist in binary or multiple systems, our understanding of how companions influence atmospheric dynamics remains limited, both observationally and numerically. In this talk, I will present recent results addressing both of these facets. First, I will discuss the observational study of the Post-Red Supergiant binary system AFGL 4106 (Tomassini et. al 2026), where we resolved the binary components and their immediate circumstellar environment using extreme adaptive optics and high-contrast imaging with VLT/SPHERE.

I will then transition to our latest theoretical efforts: modeling the impact of binarity on AGB atmospheres. Using the CO5BOLD RHD code, we modified and introduced a static binary potential to explore how a companion shapes the convective and pulsational structure of the star. These simulations try to provide an initial perspective on the impact of gravitational and centrifugal forces exerted by a companion on the structure and dynamics of AGB’s atmosphere, thereby highlighting the limitations inherent in a simplistic static potential model.