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Quantify the hydrogen CV channel’s contribution and period minima in shortest-period AM CVns

Determine the significance of the hydrogen-rich cataclysmic variable (CV) evolutionary channel in producing AM Canum Venaticorum (AM CVn) systems at the shortest orbital periods, and characterize the resulting period minima of these systems to clarify their evolutionary behavior.

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Background

The paper reviews three proposed formation channels for AM CVn systems: double white dwarf (WD), helium star, and hydrogen CV. For the hydrogen CV channel, a partially evolved main sequence donor transfers mass, gradually becoming degenerate enough to reach compact orbits and potentially very short periods.

The authors note that, unlike the other channels, the quantitative role of the hydrogen CV channel in producing the shortest-period AM CVns and the details of their period minima currently lack a well-established understanding, motivating a clearer determination of its contribution and minima behavior.

References

It is uncertain how significantly this channel contributes to the shortest-period population, and our understanding of their period minima is still evolving (Ramsay et al. 2018; Burdge et al. 2022).

— Expanding the ultracompacts: gravitational wave-driven mass transfer in the shortest-period binaries with accretion disks (2411.12796 - Chakraborty et al., 19 Nov 2024) in Section 1 (Introduction), Hydrogen CV channel