Angular momentum and mass evolution of contact binaries

Gazeas, K.; Stępień, K.

doi:10.1111/j.1365-2966.2008.13844.x

Cited by 49 publications

(42 citation statements)

References 76 publications

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“…There have been several evolutionary models of low-mass contact binaries that can explain their orbital period and mass ratio distribution, along with the difference in temperature and luminosity of the individual components (Lucy 1968;Flannery 1976;Yakut & Eggleton 2005;Stepien 2006; Gazeas & Stȩpień 2008;Stępień & Gazeas 2012;Zhang et al 2020). An important aspect of their evolution is the heat transfer in their common convective envelope, which is expected to lead to large-scale circulations of mass and thermal energy in the envelope (Stȩpień 2009).…”

Section: Introductionmentioning

confidence: 99%

Detailed evolutionary models of massive contact binaries – I. Model grids and synthetic populations for the Magellanic Clouds

Menon

Langer

Mink

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The majority of close massive binary stars with initial periods of a few days experience a contact phase, in which both stars overflow their Roche lobes simultaneously. We perform the first dedicated study of the evolution of massive contact binaries and provide a comprehensive prediction of their observed properties. We compute 2790 detailed binary models for the Large and Small Magellanic Clouds each, assuming mass transfer to be conservative. The initial parameter space for both grids span total masses from 20 to 80 M⊙ , orbital periods of 0.6 to 2 days and mass ratios of 0.6 to 1.0. We find that models that remain in contact over nuclear timescales evolve towards equal masses, echoing the mass ratios of their observed counterparts. Ultimately, the fate of our nuclear-timescale models is to merge on the main sequence. Our predicted period-mass ratio distributions of O-type contact binaries are similar for both galaxies, and we expect 10 such systems together in both Magellanic Clouds. While we can largely reproduce the observed distribution, we over-estimate the population of equal-mass contact binaries. This situation is somewhat remedied if we also account for binaries that are nearly in contact. Our theoretical distributions work particularly well for contact binaries with periods <2 days and total masses ⪅45 M⊙ . We expect stellar winds, non-conservative mass transfer and envelope inflation to have played a role in the formation of the more massive and longer-period contact binaries.

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Section: Introductionmentioning

confidence: 99%

Detailed evolutionary models of massive contact binaries – I. Model grids and synthetic populations for the Magellanic Clouds

Menon

Langer

Mink

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…We observe that for the restricted sub-population the correlation dimension of the system evolves as the system evolves in a more pronounced manner as compared to the whole population. Similar to the period-mass correlations derived in [73], this understanding can provide an estimate of f f for an unknown binary from its light curve through the calculation of D 2 and S BF. To illustrate this point, we consider a linear regression of S BF and D 2 to get an approximate value of f f .…”

Section: Correlations With Degree Of Contactmentioning

confidence: 57%

Fractal measures and nonlinear dynamics of overcontact binaries

George

Misra

Ambika

2020

Communications in Nonlinear Science and Numerical Simulation

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Overcontact binary stars are systems of two stars where the component stars are in contact with each other. This implies that they share a common envelope of gas. In this work we seek signatures of nonlinearity and chaos in these stars by using time series analysis techniques. We use three main techniques, namely the correlation dimension, f (α) spectrum and the bicoherence. The former two are calculated from the reconstructed dynamics, while the latter is calculated from the Fourier transforms of the time series of intensity variations(light curves) of these stars. Our dataset consists of data from 463 overcontact binary stars in the Kepler field of view [1]. Our analysis indicates nonlinearity and signatures of chaos in almost all the light curves. We also explore whether the underlying nonlinear properties of the stars are related to their physical properties like fill-out-factor, a measure of the extend of contact between the components of an overcontact binary system . We observe that significant correlations exist between the fill out factor and the nonlinear quantifiers. This correlation is more pronounced in specific subcategories constructed based on the mass ratios and effective temperatures of the binaries. The correlations observed can be indicative of variations in the nonlinear properties of the star as it ages. We believe that this study relating nonlinear and astrophysical properties of binary stars is the first of its kind and is an important starting point for such studies in other astrophysical objects displaying nonlinear dynamical behaviour. binary or variable [17]. Eclipsing binaries are further classified morphologically as detached and close binary star systems. Close binary systems exhibit thermal contact and have the ability to exhibit mass transfer. This offers the prospect of understanding many interesting physical phenomena like stellar mergers, thermal relaxation oscillations, magnetic stellar winds etc [18,19,20]. After the observation of a merger event in 2008 in V1309 Scorpii, considerable speculation on future merger events have lead to a deepened interest in these systems [18,21,22,23].Overcontact binaries, called W UMa stars after their prototype, are a subclass of close binary stars which shares a common envelope of gas. They are characterized by both components of the binary star exceeding their Roche lobes, implying that the companion stars are in physical contact with each other [24]. One quantity used to characterize the degree of contact in binary systems, is the fill-out factor, f f [24,25]. The fill-out factor is 0 when the component stars in the binary are just in contact and is 1 when they are in complete contact. When both components exceed their Roche lobes, as in the case of overcontact binary stars, mass and energy transfer can occur in either direction [26,27]. This can lead to changes in periods and stellar mergers leading to red novae [19,18]. While the primary variation in these stars is expected to be due to the orbital motion, many unexplained or partially e...

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“…The A-and W-type binaries differ substantially in mass ratio, and the temperature difference is usually a few hundred kelvin (Smith 1984), whereas, for some binaries, the temperature difference may be close to zero or even sometimes alternating between A-and W-type. At present, it is unconfirmed whether the division of A-and W-type is superficial or fundamental (Gazeas & Stȩpień 2008). In this case, more observations of eclipsing binaries at some special phases are expected.…”

Section: Introductionmentioning

confidence: 94%

Photometric Solutions of Three Eclipsing Binary Stars Observed from Dome A, Antarctica

Liu

Zong

et al. 2018

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Based on spectroscopic observations for the eclipsing binaries CSTAR036162 and CSTAR055495 with the WiFeS/2.3 m telescope at SSO and CSTAR057775 with the Mage/MagellanI at LCO in 2017, stellar parameters are derived. More than 100 nights of almost-continuous light curves reduced from the time-series photometric observations by CSTAR at Dome A of Antarctic in i in 2008 and in g and r in 2009, respectively, are applied to find photometric solutions for the three binaries with the Wilson-Devinney code. The results show that CSTAR036162 is a detached configuration with the mass ratio q=0.354±0.0009, while CSTAR055495 is a semi-detached binary system with the unusual q=0.946±0.0006, which indicates that CSTAR055495 may be a rare binary system with mass ratio close to one and the secondary component filling its Roche Lobe. This implies that a mass-ratio reversal has just occurred and CSTAR055495 is in a rapid mass-transfer stage. Finally, CSTAR057775 is believed to be an A-type WUMa binary with q=0.301±0.0008 and a fill-out factor of f=0.742(8).

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Angular momentum and mass evolution of contact binaries

Cited by 49 publications

References 76 publications

Detailed evolutionary models of massive contact binaries – I. Model grids and synthetic populations for the Magellanic Clouds

Detailed evolutionary models of massive contact binaries – I. Model grids and synthetic populations for the Magellanic Clouds

Fractal measures and nonlinear dynamics of overcontact binaries

Photometric Solutions of Three Eclipsing Binary Stars Observed from Dome A, Antarctica

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