On the White Dwarf Mass Problem of Cataclysmic Variables

Wei-min, Liu; Li, Xiangdong

doi:10.3847/0004-637x/832/1/80

Cited by 14 publications

(13 citation statements)

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“…Indeed, Nelemans et al (2016) found that an ejection similar to a common envelope might significantly affect the stability of mass transfer, particularly for systems with low-mass WDs. In another approach, Liu & Li (2016) calculated that if ∼ 20 − 30 per cent of the matter ejected during a nova eruption remains in the system forming a circumbinary disk, CVs with low-mass WDs would be more likely to become dynamically unstable.…”

Section: Origin Of Extra Angular Momentum Lossmentioning

confidence: 99%

“…Mass growth of the WD during the CV phase or in a preceding short phase of thermal time-scale mass transfer for many CVs was investigated in detail in Wijnen et al (2015), concluding that both options can be ruled out as the main cause for the WD mass problem (see also Liu & Li, 2016). By plotting the predicted CV population in a mass ratio (q = M sec /M WD ) versus secondary mass (M sec ) diagram it became evident that mass growth was not the solution (Schreiber et al, 2016).…”

Section: The Wd Mass Problemmentioning

confidence: 99%

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Cataclysmic variable evolution and the white dwarf mass problem: A Review

Zorotovic

Schreiber

2020

Advances in Space Research

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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, the location of the minimum period, and the space density of CVs. Moreover, it has been shown in the last decade that the average white dwarf (WD) mass observed in CVs is significantly higher than the average mass in single WDs or in detached progenitors of CVs, and that there is an absence of helium-core WDs in CVs which is not observed in their immediate detached progenitors. This highly motivated us to revise the theory of CV formation and evolution. A new empirical model for angular momentum loss in CVs was developed in order to explain the high average WD mass observed and the absence of systems with helium-core WDs. This model seems to help, at the same time, with all of the above mentioned disagreements between theory and observations. Moreover, it also provides us with a very likely explanation for the existence of low-mass WDs without a companion. Here we will review the standard model for CV evolution and the disagreements that have existed for decades between simulations and observations with their possible solutions and/or improvements. We will also summarize the recently confirmed disagreement related to the average WD mass and the fraction of helium-core WDs among CVs, as well as the development of an empirical model that allows us to solve all the disagreements, discussing the physics that could be involved.

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Section: Origin Of Extra Angular Momentum Lossmentioning

confidence: 99%

Section: The Wd Mass Problemmentioning

confidence: 99%

Cataclysmic variable evolution and the white dwarf mass problem: A Review

Zorotovic

Schreiber

2020

Advances in Space Research

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“…The detailed investigation of the process of accretion and the increase of mass in CVs, however, faces several difficulties like accretion leading to nova eruptions (thus decreasing the white dwarf mass) and the accumulated shells erupting and getting ejected. Detailed calculations show that thermaltimescale mass transfers are not effective in increasing the masses of white dwarfs in CVs (see, e.g., Liu & Li 2016). The discovery of a fast rotating and high magnetic field white dwarf in AR Sco opens up the possibility of episodic increase of mass in a CV and in the following we sketch a tentative scheme of repeated episodes of mass accretion as a reason for the high magnetic field and spin rate in AR Sco.…”

Section: Possible Evolution Of Ar Scomentioning

confidence: 86%

AR Sco as a possible seed of highly magnetized white dwarf

Mukhopadhyay

Rao

Bhatia

2017

Monthly Notices of the Royal Astronomical Society

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We explore the possibility that the recently discovered white dwarf pulsar AR Sco acquired its high spin and magnetic field due to repeated episodes of accretion and spindown. An accreting white dwarf can lead to a larger mass and consequently a smaller radius thus causing an enhanced rotation period and magnetic field. This spinning magnetic white dwarf temporarily can inhibit accretion, spin down, and, eventually, the accretion can start again due to the shrinking of the binary period by gravitational radiation. A repeat of the above cycle can eventually lead to a high magnetic field white dwarf, recently postulated to be the reason for over-luminous type Ia supernovae. We also point out that these high magnetic field spinning white dwarfs are attractive sites for gravitational radiation. MODERATELY MAGNETIZED WHITEDWARFS: PULSAR AR SCO AR Sco has been shown to be a rotating magnetised white dwarf (Marsh et al. 2016). This is argued based on various properties of it, e.g. increasing optical flux detected in radio, c 0000 RAS

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“…where η H and η He are the mass accumulation efficiencies for hydrogen and helium burning respectively, and −Ṁ 2 is the mass transfer rate. We refer to Hillman et al (2016) and Kato & Hachisu (2004) for the dependence of η H and η He on the WD mass and the mass transfer rate, respectively (see also Liu & Li 2016, for more details). The excess material is assumed to leave the binary at a rate of (|Ṁ 2 | −Ṁ WD ), taking away the specific AM of the WD.…”

Section: Modelmentioning

confidence: 99%

Can the Friction of the Nova Envelope Account for the Extra Angular Momentum Loss in Cataclysmic Variables?

Wei-min

2018

ApJ

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It has been shown that the rate of angular momentum loss (AML) in cataclysmic variables (CVs) below the period gap is about 2.47 times that caused by gravitational radiation, suggesting extra AML mechanism besides gravitational radiation. Several potential mechanisms have been proposed but none of them has been verified. In this work we examine whether AML caused by friction between the expanding nova envelope and the donor star can account for the required AML rate. By adopting various expanding velocities of the envelope, we have calculated the evolution of CVs with typical initial parameters. Our results show that this friction interaction unlikely solve the extra AML problem unless the expanding velocities are extremely low. Thus there should be a more efficient AML mechanism that plays a role in the CV evolution.

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On the White Dwarf Mass Problem of Cataclysmic Variables

Cited by 14 publications

References 50 publications

Cataclysmic variable evolution and the white dwarf mass problem: A Review

Cataclysmic variable evolution and the white dwarf mass problem: A Review

AR Sco as a possible seed of highly magnetized white dwarf

Can the Friction of the Nova Envelope Account for the Extra Angular Momentum Loss in Cataclysmic Variables?

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