Work

Off-centre convective zones in mass accreting stellar models

Year: 2025

Type: article

Abstract: We report the physical origin of transient off-centre convective zones (oCZs) that arise in mass accreting stellar models. Using detailed MESA simulations of binary evolution, we find that these oCZs are not numerical artefacts, but emerge due to a local increase in density near the retreating edge of the convective core. The density enhancement raises the local opacity, which amplifies the radiative temperature gradient ∇rad. If this gradient surpasses the Ledoux threshold ∇L, defined by both thermal and compositional stratification, the region becomes convectively unstable. The resulting oCZs are detached from the convective core and transient: mixing within the oCZ erases the local gradient in mean molecular weight and leaves a sharp ∇μ discontinuity at the boundary, thus stabilising the adjacent layers. This mechanism naturally explains the presence and evolution of oCZs, as previously reported in massive interacting stars.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202555298

Author: A. Miszuda

Language: English

Topic: Stellar, planetary, and galactic studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,865

Funders: Narodowe Centrum Nauki, Wroclawskie Centrum Sieciowo-Superkomputerowe, Politechnika Wroclawska

Award: G5950584815