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Related papers: Period bouncers as detached magnetic cataclysmic v…

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Assuming that white dwarf (WD) magnetic fields are generated by a crystallization- and rotation-driven dynamo, the impact of the late appearance of WD magnetic fields in cataclysmic variables (CVs) has been shown to potentially solve…

Solar and Stellar Astrophysics · Physics 2025-06-02 Matthias R. Schreiber , Diogo Belloni

It is predicted that half or more of all cataclysmic variables (CVs) should have evolved past the period minimum and now exist as so-called "period bouncers" where a white dwarf should be accreting from a Roche-lobe filling substellar…

Period bouncers are cataclysmic variables (CVs) that have evolved past their orbital period minimum. The strong disagreement between theory and observations of the relative fraction of period bouncers is a severe shortcoming in the…

Solar and Stellar Astrophysics · Physics 2024-06-21 Arnab Sarkar , Antonio C. Rodriguez , Sivan Ginzburg , Lev Yungelson , Christopher A. Tout

A central hypothesis in the theory of cataclysmic variable (CV) evolution is the need to explain the observed lack of accreting systems in the ~2-3 h orbital period range, known as the period gap. The standard model, disrupted magnetic…

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…

Astrophysics · Physics 2009-10-31 Ulrich Kolb , Isabelle Baraffe

Magnitude-limited samples have shown that 20-25 per cent of cataclysmic variables contain white dwarfs with magnetic fields of Mega Gauss strength, in stark contrast to the approximately 5 per cent of single white dwarfs with similar…

Solar and Stellar Astrophysics · Physics 2021-02-10 S. G. Parsons , B. T. Gänsicke , M. R. Schreiber , T. R. Marsh , R. P. Ashley , E. Breedt , S. P. Littlefair , H. Meusinger

Recent surveys of close white dwarf binaries as well as single white dwarfs have provided evidence for the late appearance of magnetic fields in white dwarfs, and a possible generation mechanism a crystallization and rotation-driven dynamo…

It has been recently suggested that white dwarfs generate magnetic fields in a process analogous to the Earth. The crystallization of the core creates a compositional inversion that drives convection, and combined with rotation, this can…

Solar and Stellar Astrophysics · Physics 2022-05-25 Sivan Ginzburg , Jim Fuller , Adela Kawka , Ilaria Caiazzo

While highly evolved cataclysmic variables (CVs) with brown dwarf donors, often called "period bouncers", are predicted to make up $\simeq40-70$ % of the Galactic CV population, only a handful of such systems are currently known. The…

Solar and Stellar Astrophysics · Physics 2018-10-01 Anna F. Pala , Linda Schmidtobreick , Claus Tappert , Boris T. Gänsicke , Andrea Mehner

Magnetic wind braking drives the spin-down of low-mass stars and the evolution of most interacting binary stars. A magnetic braking prescription that was claimed to reproduce both the period distribution of cataclysmic variables (CVs) and…

Solar and Stellar Astrophysics · Physics 2024-10-10 Valentina Ortúzar-Garzón , Matthias R. Schreiber , Diogo Belloni

Cataclysmic Variables (CV) are close binary systems, in which the primary, the more massive star, is a white dwarf. CVs usually exhibit a number of periodicities, most of which are now understood. However, recently, a new phenomenon was…

Astrophysics · Physics 2008-11-26 G. Tovmassian , S. Zharikov , V. Neustroev

Although the theory of cataclysmic variable (CV) evolution is able to explain several observational aspects, strong discrepancies have existed for decades between observations and theoretical predictions of the orbital period distribution,…

Solar and Stellar Astrophysics · Physics 2019-09-30 Monica Zorotovic , Matthias R. Schreiber

One of the most important problems in the context of cataclysmic variables (CVs) is the lack of observations of systems with periods between 2 and 3.12 hours, known as the period gap. The orbital evolution of CVs with periods shorter than…

Solar and Stellar Astrophysics · Physics 2018-11-28 C. Garraffo , J. J. Drake , J. D. Alvarado-Gomez , S. P. Moschou , O. Cohen

The origin of magnetic fields in white dwarfs remains a fundamental unresolved problem in stellar astrophysics. In particular, the very different fractions of strongly (exceeding 1 MG) magnetic white dwarfs in evolutionarily linked…

Solar and Stellar Astrophysics · Physics 2021-05-03 Matthias R. Schreiber , Diogo Belloni , Boris T. Gaensicke , Steven G. Parsons , Monica Zorotovic

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 CVs, including those which form with a brown dwarf donor star. Our models…

Astrophysics · Physics 2007-05-23 Ulrich Kolb , Isabelle Baraffe

We present measurements of the component masses in 15 Cataclysmic Variables (CVs) - 6 new estimates and 9 improved estimates. We provide new calibrations of the relationship between superhump period excess and mass ratio, and use this…

We report the discovery of two new magnetic cataclysmic variables with brown dwarf companions and long orbital periods ($P_{\rm orb}=95\pm1$ and $104\pm2$ min). This discovery increases the sample of candidate magnetic period bouncers with…

Recently, large and homogeneous samples of cataclysmic variables (CVs) identified by the Sloan Digital Sky Survey (SDSS) were published. In these samples, the famous orbital period gap, which is a dearth of systems in the orbital period…

Solar and Stellar Astrophysics · Physics 2024-02-06 Matthias R. Schreiber , Diogo Belloni , Axel D. Schwope

We apply population synthesis techniques to calculate the present day number of two types of white dwarf-main sequence star (WDMS) binaries within the cataclysmic variable period gap. The first are post-common envelope binaries with…

Astrophysics · Physics 2009-11-13 P. J. Davis , U. Kolb , B. Willems , B. T. Gänsicke

(Abridged) We present high-speed, three-colour photometry of seven short period (Porb <= 95 mins) eclipsing CVs from the Sloan Digital Sky Survey. We determine the system parameters via a parametrized model of the eclipse fitted to the…

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