Maximum eccentricity attainable under the Izzard et al. model

Determine whether the circumbinary-disc interaction model of Izzard et al. (2023) can reach the larger eccentricities observed in shell-burning stripped giant binaries beyond the eccentricity of 0.2 measured for V390 Vel.

Background

The paper reviews earlier models proposed to explain the eccentricities of post-red-giant-branch and post-asymptotic-giant-branch binaries. Although the model of Izzard et al. (2023) can reproduce the eccentricity of V390 Vel with modest adjustments, the paper identifies as unresolved whether the model can account for systems with substantially larger eccentricities. This question is relevant because the observed eccentricities extend to 0.63, whereas the model's demonstrated success is limited to an eccentricity of 0.2.

References

Furthermore, while the model presented by \citet{Izzard2023} is able to reproduce the observed eccentricity of $0.2$ for V390~Vel with some modest adjustments, it is unclear whether it can effectively reach the larger eccentricities of other SBSG binaries.

— Can circumbinary discs produce the eccentricities of shell-burning stripped giant binaries?  (2608.25762 - Moltzer et al., 26 Aug 2026) in Section 1, Introduction

Although the efficiency with which the companion accretes matter is unknown, we expect its effect on CBD-binary interaction in terms of eccentricity pumping to be negligible, similarly to accretion onto the binary as a whole (see Appendix~\ref{effect on orbital parameters}).

— Can circumbinary discs produce the eccentricities of shell-burning stripped giant binaries?  (2608.25762 - Moltzer et al., 26 Aug 2026) in Section 5, Results: accretion efficiency