Speaker
Description
Before the Gaia mission, eccentricity in wide, evolved binaries (with periods of ~10²–10⁴ days) was considered an oddity, as only a few small samples were known. Recent observations, however, reveal that eccentricity is widespread in these systems, with both the range and the maximum values of observed eccentricities increasing with orbital period. This pattern—consistent across diverse post-interaction systems such as sdB binaries, blue stragglers, and chemically polluted stars (e.g. barium, CH, and CEMP stars)—suggests a fundamental link between binary interactions and orbital eccentricity.
Despite its prevalence, the theoretical origin of eccentricity in wide post-mass-transfer binaries remains poorly understood. While several eccentricity-pumping mechanisms have been proposed, synthetic models still struggle to reproduce the observed orbital properties of these systems.
In this talk, I present the General Mass Transfer (GeMT) model, a unified semianalytical framework for the orbital evolution of mass-transferring binaries with arbitrary eccentricities. I describe the physical mechanism driving eccentricity growth during mass transfer (MT) and demonstrate that eccentric MT naturally predicts higher eccentricities at longer orbital periods, closely matching observational data. Moreover, the GeMT model predicts that post-MT eccentricities are largely independent of orbital period and depend primarily on the details of MT. Consequently, I discuss the eccentricity of post-mass-transfer systems in a broader context and argue that it should no longer be ignored or treated as a problem to be corrected, but embraced as a key observable to constrain MT.
| Talk category | NOVA Network 3 |
|---|---|
| Second preference | NOVA Network 2 |
