Characterizing non-thermal equilibrium contact binaries

Wang, Z H; Zhu, L.; Yuan, Kui

doi:10.1093/mnras/stac2629

Cited by 3 publications

(6 citation statements)

References 89 publications

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“…To find the third body for these five massive binaries, the LTTE was adopted. In this process, the observed minima are needed for these binaries; then, the theoretical minima are subtracted from the observed minima, resulting in the quantities referred to as O − C (Qian et al 2013;Wang et al 2022). The periodic oscillations in the O − C values indicate the possible presence of a third body influencing the binary system.…”

Section: Period Variations and Light Travel Time Effectmentioning

confidence: 99%

Five Massive Contact Binaries with Twin Components in LMC

Li,

Qian,

et al. 2023

ApJ

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Massive contact binaries refer to the close binary systems in which the components have filled their respective Roche lobes and share a common envelope with early-type spectra. Twin binaries are a special type of binary system characterized by two components with nearly equal masses. The Magellanic Cloud, comprising the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud, is a fascinating galaxy that is distinct from the Milky Way. With its low metallicity, it serves as an ideal test bed for studying the formation and evolution of massive binaries and testing theoretical models. In this work, based on long-term observations with Optical Gravitational Lensing Experiment and MAssive Compact Halo Object in the LMC, we identified and performed comprehensive analyses of five massive twin contact binaries via the method of the light travel time effect and Wilson–Devinney code. The results show that all of these twin binaries are accompanied by low-mass third bodies. The third bodies have minimum masses ranging from 0.33 to 1.46 M ⊙. Their orbital periods range from 4.34 to 12.03 yr. The maximum distances between the third bodies and the central binary systems range from 6.7 to 11.4 au. Remarkably, four out of the five massive twins have evolved into deep-contact binaries, which indicates that all of them may have originated from Case A mass transfer. These results strongly suggest the significant influence of the third body in the formation and evolution of massive contact binaries and may hold the key to unraveling the origins of massive binaries.

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Section: Period Variations and Light Travel Time Effectmentioning

confidence: 99%

Five Massive Contact Binaries with Twin Components in LMC

Li,

Qian,

et al. 2023

ApJ

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“…We collected samples of deep low mass ratio (DLMR) over-contact binaries from Yang & Qian (2015), where the gray dots and gray crosses represent the primary and secondary components respectively. The orange and cyan crosses stand for secondary components of STRONG t-ratio and WEAK t-ratio non-thermal equilibrium contact binaries (nTCBs) are taken from Wang et al (2022), which pointed that the STRONG t-ratio samples will evolve to WEAK t-ratio samples through heat and mass transfer along with angular momentum loss, meanwhile thickening their common envelop. Also we find in Figure 4 that there is a tendency that WEAK t-ratio nTCBs are evolving toward DLMR over-contact binaries if thermal equilibrium is continuously establishing.…”

Section: Evolutionary Propertymentioning

confidence: 99%

“…As investigated by Li & Zhang (2006), Yang & Qian (2015), Kim et al (2019), Li et al (2021a) and Christopoulou et al (2022), low mass ratio deep contact binaries have a relationship between J spin /J orb and q. To better understand the character of samples with large temperature difference between two components, we also revisited samples of nTCBs from Wang et al (2022) and figured out their J spin /J orb at k 2 = 0.05. We constructed the q − J spin /J orb diagram and discriminated the unstable region and stable region of contact binaries by the Bressan et al (2012).…”

Section: Evolutionary Propertymentioning

confidence: 99%

“…The blue and red dots with err bars are the primary and secondary component of J0103. The background gray dots and gray crosses represent the primary and secondary components of deep low mass ratio (DLMR) over-contact binaries taken from Yang & Qian (2015); the orange and cyan crosses stand for secondary components of STRONG t-ratio and WEAK t-ratio non-thermal contact binaries (nTCBs) are taken from Table A2 in Wang et al (2022), where the STRONG t-ratio samples to those with relative temperature difference (t-ratio), (T 1 − T 2 )/T 1 > 0.2 and the WEAK t-ratio samples to those 0.05 < t-ratio = (T 1 − T 2 )/T 1 < 0.2. boundary of J orb = 3J spin (blue dashed line in Figure 5). From the figure we can find that STRONG t-ratio samples are mostly distributed between the q value of 0.25 and 0.6, whereas the WEAK t-ratio samples are located mostly in both sides.…”

Section: Evolutionary Propertymentioning

confidence: 99%

“…They are non-thermal contact binaries (nTCBs) where the components are in poor thermal contact (Rucinski & Duerbeck 1997). Based on a statistical work of 80 nTCBs, Wang et al (2022) noticed an evolutionary channel from strong t-ratio samples to weak t-ratio samples, during which process their common envelop will thicken. This evolutionary status has been predicted by the thermal relaxation oscillation (TRO, Lucy 1976;Flannery 1976;Robertson & Eggleton 1977) theory, whereas more issues remain obscure.…”

Section: Introductionmentioning

confidence: 99%

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1SWASP J010313.78+352903.7: A Totally Eclipsing Binary with Components in Poor Thermal Contact

Wang

Zhu²,

Yuan³

2022

Res. Astron. Astrophys.

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We presented photometry for an EB-type totally eclipsing binary, 1SWASP J010313.78+352903.7, observed with the Xinglong 85-cm telescope on Oct 22, 2021. Light curves in five bands (including the TESS data) were analyzed by employing the W-D method. The photometric solutions show that it is a contact binary with a relatively low mass ratio (q ≃ 0.28), relatively large fill-out factor (f ≃ 40%) and large temperature difference (∆ T ≃ 1700K). Max.I-Max.II is up to about 9% of variable light amplitude of the asymmetric light curves. It is well described by double-hot spots model on the surface of the cooler secondary. The two hot spots are both in growing and evolving. They may be caused by two different mechanics, i.e. magnetic stellar activity and mass transfer. The large temperature difference between the two contact components indicates that they share a non-thermal equilibrium common envelope.

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Investigation of a W UMa-type contact binary GZ And in a physical triple system

Jiang,

Zheng

2024

Front. Astron. Space Sci.

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GZ And is a variable star within the visually observed multiple-star system ADS 1693. Recent observations have yielded new light curves for GZ And, obtained using the Xinglong 85-cm telescope and the Transiting Exoplanet Survey Satellite (TESS) satellite. These light curves, along with radial velocity curves, were analyzed simultaneously to ascertain the fundamental physical parameters of GZ And’s components. The findings indicate that the primary star has a mass of M1 = 0.57 (4)M⊙, radius of R1 = 0.75 (2)R⊙, and luminosity of L1 = 0.42 (2)L⊙. The secondary star is characterized by a mass of M2 = 1.19 (9)M⊙, radius of R2 = 1.04 (3)R⊙, and luminosity of L2 = 0.63 (3)L⊙. Their orbital separation is determined to be a = 2.30 (6)R⊙. An analysis of the accumulated times of light minima reveals that GZ And is undergoing orbital period variations at a rate of dP/dt = −7.58 (7) × 10−8day ⋅ year−1, likely due to mass transfer from the more massive component to its lighter counterpart at a rate of dM2/dt = −9.06 (8) × 10−8M⊙⋅ year−1. Additionally, distance measurements for the component stars in ADS 1693, derived from Gaia DR3 astrometric data, suggest that ADS 1693A (GZ And) and ADS 1693B are gravitationally bound and likely originated from the same molecular cloud, sharing similar ages. This evidence supports the classification of GZ And as a W UMa-type contact binary within a physically associated triple system.

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Characterizing non-thermal equilibrium contact binaries

Cited by 3 publications

References 89 publications

Five Massive Contact Binaries with Twin Components in LMC

Five Massive Contact Binaries with Twin Components in LMC

1SWASP J010313.78+352903.7: A Totally Eclipsing Binary with Components in Poor Thermal Contact

Investigation of a W UMa-type contact binary GZ And in a physical triple system

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