A Unique Low-mass-ratio Contact Eclipsing Binary System under the Period Cutoff

Papageorgiou, Athanasios; Christopoulou, Panagiota-Eleftheria; Lalounta, Eleni; Ferreira Lopes, C. E.; Catelan, Márcio; Drake, Andrew J.; Ηantzios, Panayiotis; Alikakos, Ioannis

doi:10.3847/1538-4357/acdcf3

Cited by 2 publications

(1 citation statement)

References 45 publications

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“…This is why several studies of ETV analysis were not supported by the most recent data. Papageorgiou (2015) and Papageorgiou & Christopoulou (2015) suggested a fitting strategy for O − C analysis that incorporates optimization methods to explore the parameter space such as genetic algorithms (GAs;Holland 1975;Charbonneau 1995), heuristic scanning with parameter perturbation, the combination of Nelder-Mead downhill simplex and Levenberg-Marquardt (NMS-LM) algorithms, and Markov Chain Monte Carlo (MCMC)/Monte Carlo-based methods for error budget and parameter determination (Papageorgiou et al 2023). Parimucha et al (2018) and Gajdoš & Parimucha (2019) also proposed a fitting strategy that uses GA optimization followed by MCMC fitting for the O − C analysis of extrasolar planets and Algoltype EBs.…”

Section: Introductionmentioning

confidence: 99%

Investigating Period Variability Mechanisms in Eclipsing Binary Stars through Eclipsing Time Variation Analysis: A Case Study of TZ Bootis

Zervas,

Christopoulou,

Papageorgiou

2024

ApJ

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We present an effective strategy for extensive analysis of eclipsing time variations (ETVs) using modern and sophisticated optimization methods that comprise a set of tools to investigate period variability mechanisms in eclipsing binary stars such as the light-time effect, the Applegate mechanism, and mass transfer. We implement these methods for the first time assuming that the above mechanisms can act simultaneously in the puzzling W UMa–type binary star TZ Bootis by using archival and new TESS data spanning 75 yr and reexamining the up-to-date ETVs. Preliminary analysis of the TESS data revealed for the first time the presence of a second binary in agreement with previous spectroscopic data and astrometric results from Gaia DR3. We consider the most credible scenario for the ETV: two stellar circumbinary companions of minimum masses M 3 = 0.5 M ☉ and M 4 = 0.14 M ☉ in highly eccentric orbits e 3 = 0.70 and e 4 = 0.82 with periods P 3 = 38 yr and P 4 = 20 yr along with a 24 yr magnetic activity of the secondary component and a long-term period increase (dP/dt = 1.2 × 10−8 days yr−1), interpreted as a conservative mass transfer from the secondary to the primary component at a rate of dM 1/dt = 3.7 × 10−9 days yr−1. Further spectroscopic observations, analytical modeling of the second pair, and ETV analysis of both pairs are needed to investigate the quadruple nature of the system.

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Section: Introductionmentioning

confidence: 99%

Investigating Period Variability Mechanisms in Eclipsing Binary Stars through Eclipsing Time Variation Analysis: A Case Study of TZ Bootis

Zervas,

Christopoulou,

Papageorgiou

2024

ApJ

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The critical mass ratio for W UMa-type contact binary systems

Arbutina,

Wadhwa

2024

SERBIAN ASTRON J

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Contact binaries are close binary systems in which both components fill their inner Roche lobes so that the stars are in direct contact, and in potential mass and energy exchange. The most common such systems of low mass are the so-called W UMa-type. In the last few years, there has been a growing interest of the astronomical community in stellar mergers, primarily due to the detection of gravitational waves (mergers of black holes and neutron stars), but also because of an alternative model for the type Ia supernovae (merger of two white dwarfs), which are again particularly important in cosmology where they played a significant role in the discovery of dark energy and the accelerated expansion of the Universe. In that sense, contact systems of W UMa type with extremely low mass ratio are especially interesting because there are indications that, in their case too, stars can merge and possibly form fast-rotating stars such as FC Com stars and the blue-stragglers, and (luminous) red novae such as V1309 Sco. Namely, the previous theoretical research has shown that in the cases when the orbital angular momentum of the system is only about three times larger than the rotational angular momentum of the primary, a tidal Darwin's instability occurs, the components can no longer remain in synchronous rotation, orbit continue to shrink fast, and they finally merge into a single star. The above stability condition for contact systems can be linked to a specific critical mass ratio below which we expect a system to be unstable. We give an overview of this condition and show how it can be used to identify potential mergers. Finally, we discuss a number of known extreme mass ratio binaries from the literature and consider prospects for future research on this topic.

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A Unique Low-mass-ratio Contact Eclipsing Binary System under the Period Cutoff

Cited by 2 publications

References 45 publications

Investigating Period Variability Mechanisms in Eclipsing Binary Stars through Eclipsing Time Variation Analysis: A Case Study of TZ Bootis

Investigating Period Variability Mechanisms in Eclipsing Binary Stars through Eclipsing Time Variation Analysis: A Case Study of TZ Bootis

The critical mass ratio for W UMa-type contact binary systems

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