A unified theory of cataclysmic variable evolution from feedback-dominated numerical simulations


The envelopes accreted by white dwarf stars from their hydrogen-rich companions1 experience thermonuclear-powered runaways2,3 observed as classical nova eruptions4,5 peaking at 105–106 solar luminosities6,7,8,9. Virtually all nova progenitors—‘nova-like variables’—exhibit high mass transfer rates to their white dwarfs before and after an eruption10. Surprisingly, 10–1,000 times lower mass transfer rate11 binaries, exhibiting accretion-powered ‘dwarf nova’ outbursts12, exist at identical orbital periods. Nova shells surrounding dwarf novae13,14,15,16 demonstrate that at least some novae metamorphize into dwarf novae17,18, though the mechanisms and timescales governing mass transfer rate variations are poorly understood. Here, we report simulations of the multi-Gyr evolution of novae modelling every eruption’s thermonuclear runaway, mass and angular momentum losses, feedback due to irradiation and variable mass transfer rate, and orbital size and period changes. These feedback-dominated simulations reproduce the observed range of mass transfer rates at a given orbital period, with large and cyclic kyr–Myr timescale changes. They also demonstrate Myr-long deep hibernation (complete stoppage of mass transfer), but only in short-period binaries; that initially different binaries converge to become nearly identical systems; low-mass-transfer-rate dwarf novae occasionally generate novae; and that the masses of white dwarfs decrease monotonically, but only slightly while their red dwarf companions are consumed.

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Fig. 1: Cyclic variation of the accretion rate onto the white dwarf during nine individual nova cycles spanning the entire, multi-Gyr evolution for each of the four models listed in Table 1.
Fig. 2: Long-term changes for the four models in Table 1.
Fig. 3: Percentage of nova eruptions for which a binary system is found in an orbital period interval, for each of the four models.
Fig. 4: Percentage of cataclysmic variable binary system lifetime spent at different orbital periods.

Data availability

All data pertaining to each simulation is available upon reasonable request from Y.H.


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We thank the dozens of observers who have worked diligently, over the past three decades, to test predictions of the hibernation scenario of cataclysmic variables. We also thank C. Tappert, L. Schmidtobreick, B. Schaefer and C. Knigge for valuable constructive criticisms of an earlier draft of this paper.

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All authors shared in formulating the ideas underlying the simulations, the computer algorithms and the writing of this paper. Y.H. carried out the simulations and the data mining that produced the figures.

Corresponding authors

Correspondence to Yael Hillman or Michael M. Shara.

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The authors declare no competing interests.

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Peer review information Nature Astronomy thanks Jordi Jose and Steven Shore for their contribution to the peer review of this work.

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Hillman, Y., Shara, M.M., Prialnik, D. et al. A unified theory of cataclysmic variable evolution from feedback-dominated numerical simulations. Nat Astron (2020). https://doi.org/10.1038/s41550-020-1062-y

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