Off-centre convective zones in mass accreting stellar models
Fuente:
arXiv
Saved in:
| Main Author: | |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866908542423793664 |
|---|---|
| author | Miszuda, A. |
| author_facet | Miszuda, A. |
| contents | 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 $\nabla_{\rm rad}$. If this gradient surpasses the Ledoux threshold $\nabla_{\rm L}$, 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, leaving a sharp $\nabla_μ$ discontinuity at the boundary, stabilizing the adjacent layers. This mechanism naturally explains the presence and evolution of oCZs, as previously reported in massive interacting stars. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_14121 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Off-centre convective zones in mass accreting stellar models Miszuda, A. Solar and Stellar Astrophysics High Energy Astrophysical Phenomena 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 $\nabla_{\rm rad}$. If this gradient surpasses the Ledoux threshold $\nabla_{\rm L}$, 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, leaving a sharp $\nabla_μ$ discontinuity at the boundary, stabilizing the adjacent layers. This mechanism naturally explains the presence and evolution of oCZs, as previously reported in massive interacting stars. |
| title | Off-centre convective zones in mass accreting stellar models |
| topic | Solar and Stellar Astrophysics High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2508.14121 |