Brown Dwarfs and the Cataclysmic Variable Period Minimum

Ulrich Kolb; Isabelle Baraffe

doi:10.1046/j.1365-8711.1999.02926.x

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arXiv · astro-ph/9906448

Brown Dwarfs and the Cataclysmic Variable Period Minimum

Ulrich Kolb·Isabelle Baraffe

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Abstract

Using improved, up-to-date stellar input physics tested against observations of low-mass stars and brown dwarfs we calculate the secular evolution of low-mass donor cataclysmic variables (CVs), including those which form with a brown dwarf donor. Our models confirm the mismatch between the calculated minimum period (Pmin ~ 70 min) and the observed short-period cut-off (~ 80 min) in the CV period histogram. We find that tidal and rotational corrections applied to the one-dimensional stellar structure equations have no significant effect on the period minimum. Theoretical period distributions synthesized from our model sequences always show an accumulation of systems at the minimum period, a feature absent from the observed distribution. We suggest that non-magnetic CVs become unobservable as they are effectively trapped in permanent quiescence before they reach Pmin, and that small-number statistics may hide the period spike for magnetic CVs.

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Ulrich Kolb, Isabelle Baraffe. 1999-06-28. Brown Dwarfs and the Cataclysmic Variable Period Minimum. https://doi.org/10.1046/j.1365-8711.1999.02926.x

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