Model angular-momentum loss from the hot nova envelope

Develop an accurate theoretical model of angular-momentum loss during nova eruptions, including the three-dimensional interaction between the companion star and the hot envelope surrounding the white dwarf, in order to calculate the resulting orbital-period change.

Background

The paper argues that angular-momentum loss during nova eruptions is dominated not by the traditional fast-ejecta dynamical-friction mechanism but by the interaction of the companion star with a hot, extended envelope around the white dwarf. This interaction can strongly affect the orbital-period change and is particularly important for short-period novae with low-mass white dwarfs such as V1405 Cas.

The authors state that the envelope structure is poorly known and that the companion–envelope interaction requires a complex three-dimensional calculation. Consequently, the angular-momentum-loss contribution cannot currently be predicted accurately from first principles, forcing the analysis to rely on analogies with the twin novae HR Del and RR Pic.

References

Unfortunately, this new mechanism cannot yet be accurately modeled with theory.

— Classical Nova V1405 Cas Had $M_{\rm ejecta}$$>$$M_{\rm accreted}$ and so is Unlikely to be a Type Ia Supernova Progenitor  (2609.10990 - Schaefer, 10 Sep 2026) in Section 4.5, “The New ΔP_aml Mechanism That Dominates”