Description
Before the launch of Gaia, eccentricity in wide evolved binaries (with periods of ~10²–10⁴ days) was considered an oddity, as only a few small samples were known. These observations have revealed that many of these systems are eccentric, with the range of observed eccentricities increasing with orbital period. Notably, the maximum observed eccentricities also rise as the orbital period grows. This pattern, observed across various post-interaction systems—including sdB binaries (Vos et al. '17, Molina '22), blue stragglers (Geller and Mathieu '11, Mathieu and Geller '19), chemically-polluted stars, such as, Barium stars (Jorissen et al. '98, '19, Escorza et al. '19) and carbon-enhanced metal-poor stars (Jorissen et al. '15, '16, Hansen et al. '16, '19)—suggests a fundamental link between binary interactions and eccentricity. With recent Gaia discoveries, a picture has emerged in which eccentricity appears to be a universal feature of wide evolved binaries. However, their formation remains a challenge, as existing models fail to reproduce both their long periods and high eccentricities.
In this talk, I will present the General Mass Transfer (GeMT) model, a unified analytic framework for the orbital evolution of mass-transferring binaries. The GeMT model applies to both conservative and non-conservative mass transfer in circular and eccentric orbits. I will compare its predictions with previous models in the conservative mass transfer limit and discuss new insights into the stability criteria of mass transfer. Finally, I will show that the GeMT model naturally predicts wide and eccentric orbits, closely matching the observed properties of these binary populations.
| Talk category | NOVA Network 3 |
|---|---|
| Preference for a talk or poster | Talk |
| Talk preference for PhD students | second year |
