A possible relation between the period change and the mass ratio for W-type contact binaries

Qian, S.‐B.

doi:10.1046/j.1365-8711.2001.04931.x

Cited by 129 publications

(83 citation statements)

References 51 publications

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“…Evidently, the simplistic β − q schemes seem to be insufficient in describing the short orbital evolution of a binary in which MT is not the leading evolutionary mechanism. This may be consistent with the findings of Qian (2001), who has shown that a critical value close to q cr ≈ 0.40 appears to invert the monotonicity of the observed orbital evolution in contact binaries. However, this did not emerge clearly from the present study.…”

Section: Discussionsupporting

confidence: 92%

Efficiency of ETV diagrams as diagnostic tools for long-term period variations

Nanouris

Kalimeris

Antonopoulou

et al. 2015

A&A

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Context. The credibility of an eclipse timing variation (ETV) diagram analysis is investigated for various manifestations of the mass transfer and gravitational radiation processes in binary systems. The monotonicity of the period variations and the morphology of the respective ETV diagrams are thoroughly explored in both the direct impact and the accretion disk mode of mass transfer, accompanied by different types of mass and angular momentum losses (through a hot-spot emission from the gainer and via the L2/L3 points). Aims. Our primary objective concerns the traceability of each physical mechanism by means of an ETV diagram analysis. Also, possible critical mass ratio values are sought for those transfer modes that involve orbital angular momentum losses strong enough to dictate the secular period changes even when highly competitive mechanisms with the opposite direction act simultaneously. Methods. TheJ −Ṗ relation that governs the orbital evolution of a binary system is set to provide the exact solution for the period and the function expected to represent the subsequent eclipse timing variations. The angular momentum transport is parameterized through appropriate empirical relations, which are inferred from semi-analytical ballistic models. Then, we numerically determine the minimum temporal range over which a particular mechanism is rendered measurable, as well as the critical mass ratio values that signify monotonicity inversion in the period modulations. Results. Mass transfer rates comparable to or greater than 10 −8 M yr −1 are measurable for typical noise levels of the ETV diagrams, regardless of whether the process is conservative. However, the presence of a transient disk around the more massive component defines a critical mass ratio (q cr ≈ 0.83) above which the period turns out to decrease when still in the conservative regime, rendering the measurability of the anticipated variations a much more complicated task. The effects of gravitational radiation proved to be rather undetectable, except for systems with physical characteristics that only refer to cataclysmic variables. Conclusions. The monotonicity of the period variations and the curvature of the respective ETV diagrams depend strongly on the accretion mode and the degree of conservatism of the transfer process. Unlike the hot-spot effects, the Lagrangian points L2 and L3 support very efficient routes of strong angular momentum loss. It is further shown that escape of mass via the L3 point -when the donor is the less massive component -safely provides critical mass ratios above which the period is expected to decrease, no matter how intense the process is.

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Section: Discussionsupporting

confidence: 92%

Efficiency of ETV diagrams as diagnostic tools for long-term period variations

Nanouris

Kalimeris

Antonopoulou

et al. 2015

A&A

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“…Based on the period changes of 30 W-subtype contact binaries, Qian (2001) found that systems showing period increase usually have a higher mass ratio (q > 0.4), while the period of low-mass ratio systems (q < 0.4) show secular decreases. The conclusion was later expanded by Qian (2003) to both W-and A-subtype contact binaries who gave the relations between the period variation and the mass ratio and the orbital period.…”

Section: Discussionmentioning

confidence: 99%

A Charge-Coupled Device Photometric Study of South Hemispheric Contact Binary Ae Phoenicis

He¹,

Qian²,

Lajús³

et al. 2009

The Astronomical Journal

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The complete charge-coupled device light curves in B, V, R, and I bands of the short-period binary system, AE Phe, are presented. It is found that the light curves of AE Phe belong to typical EW-type light variation. Photometric solutions were derived by using the 2003 version of the Wilson-Devinney code. It showed that AE Phe is a Wsubtype shallow-contact system (f = 14.6%(±0.5%)) with a mass ratio of q = 2.5491(±0.0092). The temperature difference between the two components is 227 K. Analysis of the O − C curve suggests that the period of AE Phe shows a long-term continuous increase at a rate of dP /dt = +6.17(±0.44) × 10 −8 days year −1 . The longterm period increase, the marginal-contact configuration, and the astrophysical parameters of the binary system, all suggest that it is a shallow-contact binary undergoing a thermal relaxation oscillation evolving into a detached binary.

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“…As one can see from this table, the values of the period changes of NY Lyr are typical among the four binary stars. The recent period studies by Qian (2001aQian ( ,b, 2003 showed that the period change of W UMa-type binaries may correlate with the mass ratio of the system and with the mass of the primary component.…”

Section: Discussionmentioning

confidence: 99%

“…It is well known that orbital period changes of W UMa-type binaries are very common (e.g. Qian 2001aQian ,b, 2003. For NY Lyr, the O-C diagram published by Kreiner et al (2001) suggested that its orbital period is changeable.…”

Section: Introductionmentioning

confidence: 99%

Complex Period Variations of the Neglected W UMa-type Binary System NY Lyrae

Qian

Liu

Zhu

2009

Publ. – Astron. Soc. Aust

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Abstract:Orbital-period variations of the neglected W UMa-type binary star, NY Lyr, were analyzed based on two newly determined eclipse times together with the others compiled from the literature. A cyclic oscillation with a period of 82.1 yr and an amplitude of 0.0247 d was discovered to be superimposed on a continuous period increase (dP/dt = +1.33 × 10 −7 d yr −1 ). After the long-term period increase and the large-amplitude cyclic oscillation were removed from the O-C diagram, the residuals suggest that there is another smallamplitude period oscillation (A 4 = 0.0053 d, P 4 = 19.4 years) in the orbital period changes. As in the cases of AH Cnc and AD Cnc, both the continuous period increase and the two cyclic period oscillations make NY Lyr an interesting system to study in the future. In order to understand the evolutionary state of the binary system, new photometric and spectroscopic observations and a careful investigation on those data are needed.

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A possible relation between the period change and the mass ratio for W-type contact binaries

Cited by 129 publications

References 51 publications

Efficiency of ETV diagrams as diagnostic tools for long-term period variations

Efficiency of ETV diagrams as diagnostic tools for long-term period variations

A Charge-Coupled Device Photometric Study of South Hemispheric Contact Binary Ae Phoenicis

Complex Period Variations of the Neglected W UMa-type Binary System NY Lyrae

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