The dynamical stability of W Ursae Majoris-type systems

Li, Lifang; Zhang, Fenghui

doi:10.1111/j.1365-2966.2006.10462.x

Cited by 67 publications

(45 citation statements)

References 25 publications

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“…Rasio (1995) chose 𝑘 = 0.245, such that the lowest mass ratio system known at the time, AW UMa with 𝑞 = 0.075 (Rucinski 1992) would be stable, and did not take into account the spin momentum of the secondary when arriving at the global critical mass ratio. As more systems with mass ratios below the estimated critical value were discovered, researchers tried to modify the calculations either to include the spin momentum of the secondary (Li & Zhang 2006) or to use different values of 𝑘 (Jiang et al 2010).…”

Section: Instability Mass Ratio Of Contact Binary Systemsmentioning

confidence: 99%

ZZ Piscis Austrinus (ZZ PsA): a bright red nova progenitor and the instability mass ratio of contact binary stars

Wadhwa

Horta

Filipović

et al. 2020

Monthly Notices of the Royal Astronomical Society

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ZZ PsA is a neglected bright southern contact binary system with maximum V magnitude of 9.26. We present the first multi-band photometric analysis and find the system to be in deep contact (>95%) with an extremely low mass ratio of 0.078. The primary has a mass of 1.213 M⊙ in keeping with its reported spectral class of F6. In order to determine if ZZ PsA is a merger candidate we outline the current status regarding the instability mass ratio and develop new relationship linking the mass of the primary to the instability mass ratio of the system and the degree of contact. We find that ZZ PsA along with two other examples from the literature to be merger candidates while an additional three require further observations to be confirmed as potential merger candidates.

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Section: Instability Mass Ratio Of Contact Binary Systemsmentioning

confidence: 99%

ZZ Piscis Austrinus (ZZ PsA): a bright red nova progenitor and the instability mass ratio of contact binary stars

Wadhwa

Horta

Filipović

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…The distribution of mass ratio in short-period P <100 d detached systems with ≈1 M primaries (progenitors of contact systems) is observed to be nearly uniform (Niu et al 2020;Moe & Di Stefano 2017), so deviations from a uniform distribution in contact systems must be a consequence of evolution. The most commonly cited modification that is expected is a lower limit on mass ratio due to the Darwin instability (Darwin 1893), generally taken to be a fixed value around 0.09 (Rasio 1995) or ≈0.07 (Arbutina 2009;Li & Zhang 2006). The evolutionary models of Molnar et al (2019); Molnar (2022) yield orbital period dependence of this minimum, along with period dependences of a maximum q a and of typical q a values.…”

Section: The Dependence Of Mass Ratio On Period For Contact Binariesmentioning

confidence: 99%

A Bayesian Analysis of Physical Parameters for 783 Kepler (Near-)Contact Binaries: Extreme-Mass-Ratio Systems and a New Mass Ratio versus Period Lower Limit

Kobulnicky,

Molnar,

Cook

et al. 2022

Preprint

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Contact binary star systems represent the long-lived penultimate phase of binary evolution. Population statistics of their physical parameters inform understanding of binary evolutionary pathways and end products. We use light curves and new optical spectroscopy to conduct a pilot study of ten (near-)contact systems in the long-period (P >0.5 d) tail of close binaries in the Kepler field. We couple PHOEBE light curve models with Markov-Chain Monte Carlo analyses to compute Bayesian probabilities on inclinations, fillout factors, mass ratios, third-light fractions, and component temperature ratios. Mass ratios and third-light contributions measured from spectra agree well with those inferred from the light curves. Most binaries in the pilot study have extreme mass ratios q<0.32. At least eight are probable triples. A Bayesian analysis of all 783 Kepler 0.15 d

0.5 d, as are systems with mass ratios near unity (q>0.8). There exists an empirical mass ratio lower limit q min (P )≈0.05-0.15 below which contact systems are absent, in agreement with a new set of theoretical predictions we obtain by modeling the evolution of contact systems under the constraints of mass and angular momentum conservation. Pre-merger systems should be found at at long periods and near this mass ratio lower limit, which rises from q=0.044 for P =0.74 d to q=0.15 at P =2.0 d. These findings support a scenario whereby mass transfer drives systems toward extreme q and larger P until the onset of the Darwin instability at q min precipitates a merger.

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“…To investigate the stability of the 30 new LMRs listed in Tables 1-3, we determine this ratio using the formula derived from eq. ( 1) and (2) of Li & Zhang (2006)…”

Section: Premerger Candidatesmentioning

confidence: 99%

New low mass ratio contact binaries in the Catalina Sky Survey

Christopoulou,

Lalounta,

Papageorgiou

et al. 2022

Preprint

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We present the identification and photometric analysis of 30 new low mass ratio (LMR) totally eclipsing contact binaries found in Catalina Sky Survey data. The LMR candidates are identified using Fourier coefficients and visual inspection. We perform a detailed scan in the parameter plane of mass-ratio (𝑞) versus inclination (𝑖) using Phoebe-0.31 scripter to derive the best (𝑞, 𝑖) pair for the initial models. The relative physical parameters are determined from the final model of each system. A Monte-Carlo approach was adopted to derive the parameter errors. The resulting parameters confirm the identification. The approximate absolute physical parameters of the systems are estimated based on the light curve solutions and Gaia early Data Release 3 distances. Twelve out of 30 new systems have fill-out factors 𝑓 > 50% and 𝑞 ≤ 0.25 (deep contact LMR systems), and 8 of them, to within errors, are extreme LMR deep systems with 𝑞 ≤ 0.1. We discuss the evolutionary status of the 30 LMR systems in comparison with the most updated catalog of LMR systems from the literature. The scenario of the LMR systems as pre-merger candidates forming fast rotating stars is investigated for all systems, new and old, based both on Hut's stability criteria and critical instability mass ratio (𝑞 inst ) relation. CSS_J075848.2+125656, with 𝑞/𝑞 inst = 1.23 ± 0.23, and CSS_J093010.1-021624, with 𝑞/𝑞 inst = 1.25 ± 0.23, can be considered as merger candidates.

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The dynamical stability of W Ursae Majoris-type systems

Cited by 67 publications

References 25 publications

ZZ Piscis Austrinus (ZZ PsA): a bright red nova progenitor and the instability mass ratio of contact binary stars

ZZ Piscis Austrinus (ZZ PsA): a bright red nova progenitor and the instability mass ratio of contact binary stars

A Bayesian Analysis of Physical Parameters for 783 Kepler (Near-)Contact Binaries: Extreme-Mass-Ratio Systems and a New Mass Ratio versus Period Lower Limit

New low mass ratio contact binaries in the Catalina Sky Survey

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