Ultrashort-Period Binaries, Gravitational Radiation, and Mass Transfer. I. The Standard Model, with Applications to WZ Sagittae and Z Camelopardalis

Faulkner, John

doi:10.1086/180848

Cited by 204 publications

(110 citation statements)

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“…Gravitational radiation could explain the formation of cataclysmic variables (CVs) with orbital periods less than 3 h, while magnetic braking of the tidally coupled primary by its own magnetic wind would account for orbital angular-momentum loss from CVs with periods up to 10 h (Faulkner 1971;Zangrilli et al 1997). We use the formula for the rate of angular-momentum loss due to magnetic braking derived by Rappaport et al (1983) and Skumanich (1972):…”

Section: Gravitational Radiation and Magnetic Brakingmentioning

confidence: 99%

The gravitational wave signal from diverse populations of double white dwarf binaries in the Galaxy

Jeffery

2010

A&A

130

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Context. The gravitational wave (GW) background in the range 0.01−30 mHz has been assumed to be dominated by unresolved radiation from double white dwarf binaries (DWDs). Recent investigations indicate that, at short periods, a number of DWDs should be resolvable sources of GW. Aims. We characterize the GW signal which would be detected by LISA from DWDs in the Galaxy. Methods. We have constructed a Galactic model in which we consider distinct contributions from the bulge, thin disc, thick disc, and halo, and subsequently executed a population synthesis approach to determine the birth rates, numbers, and period distributions of DWDs within each component. Results. In the Galaxy as a whole, our model predicts the current birth rate of DWDs to be 3.21 × 10 −2 yr −1 , the local density to be 2.2 × 10 −4 pc −3 and the total number to be 2.76 × 10 8 . Assuming SNIa are formed from the merger of two CO white dwarfs, the SNIa rate should be 0.0013 yr −1 . The frequency spectra of DWD strain amplitude and number distribution are presented as a function of galactic component, DWD type, formation channel, and metallicity. Conclusions. We confirm that CO+He and He+He white dwarf (WD) pairs should dominate the GW signal at very high frequencies (log f Hz −1 > −2.3), while CO+CO and ONeMg WD pairs have a dominant contribution at log f Hz −1 ≤ −2.3. Formation channels involving two common-envelope (CE) phases or a stable Roche lobe overflow phase followed by a CE phase dominate the production of DWDs detectable by LISA at log f Hz −1 > −4.5. DWDs with the shortest orbital periods will come from the CE+CE channel. The Exposed Core plus CE channel is a minor channel. A number of resolved DWDs would be detected, making up 0.012% of the total number of DWDs in the Galaxy. The majority of these would be CO+He and He+He pairs formed through the CE+CE channel.

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Section: Gravitational Radiation and Magnetic Brakingmentioning

confidence: 99%

The gravitational wave signal from diverse populations of double white dwarf binaries in the Galaxy

Jeffery

2010

A&A

130

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“…The behavior of low-mass components of CB evolving under the influence of AML via GWR, like for "usual" hydrogen-rich cataclysmic variables, is defined by the relation between the timescale of stellar evolution τ ev , thermal timescale of the star τ KH and AML timescale τ GW (Faulkner, 1971;Paczyński, 1981;Savonije et al, 1986). The relation between the timescales itself depends on the mass of the star, its evolutionary state at RLOF and total mass of the binary (see Fig.…”

Section: Evolution Of Helium Starsmentioning

confidence: 99%

“…these results will be applied for the analysis of the origin of observed AM CVn stars. 4 He, 12 C, 14 N, 16 O, 20 Ne, 24 Mg are computed. The nuclear reactions network is given in Table 1 It was assumed that mass-exchange is conservative.…”

Section: Introductionmentioning

confidence: 99%

Evolution of low-mass helium stars in semidetached binaries

Yungelson

2008

Astron. Lett.

142

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We present results of a systematic investigation of the evolution of low-mass (0.35 M ⊙ , 0.40 M ⊙ and 0.65 M ⊙ ) helium donors in semidetached binaries with accretors -white dwarfs. In the initial models of evolutionary sequences abundance of helium in the center 0.1 < ∼ Y c ≤ 0.98. Results of computations may be applied to the study of the origin and evolutionary state of AM CVn stars. It is shown that the minimum orbital periods of the systems only weakly depend on the total mass of the system and evolutionary state of the donor at RLOF and are equal to 9-11 min. The scatter in the mass-exchange rates at given P orb in the range P orb,min < P orb ∼ 40 min. the timescale of mass-loss begins to exceed thermal time-scale of the donors, the latter begin to contract, they become more degenerate and, apparently, "white-dwarf" and "helium-star" populations of AM CVn stars merge.

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“…The radiation is strongest at periastron, and thus radiation reaction tends to circularize the orbit. If gravitational radiation is the dominant force changing the orbital period, and if the orbit is nearly circular, then the orbital period will decrease at the rate However, the problem for short-period binaries is more complex: As the orbit shrinks by radiation reaction, one star may encroach on the other's Roche surface, leading to a mass transfer from one star to the other, which can markedly effect the evolution of the system (Faulkner 1971, Vila 1971). …”

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confidence: 99%