Period variation and spot model for the W UMa type binary TY UMa

Kang, Yong; Oh, Kyu-Dong; Kim, Chun-Hwey; Hwang, Changdeok; Kim, Ho-il; Lee, Woo-Baik

doi:10.1046/j.1365-8711.2002.05246.x

Cited by 35 publications

(12 citation statements)

References 9 publications

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“…The period gap is indicated by vertical dashed lines. The crosses depict ∆P/P values for 56 other close binaries with cyclical period modulations (Lanza & Rodonó 1999;Qian et al 1999Qian et al , 2000aQian et al ,b, 2002Qian et al , 2007aLanza et al 2001;Kang et al 2002;Qian 2002aQian ,b, 2003Yang & Liu 2002, 2003aZavala et al 2002;Çakırlı et al 2003;Kim et al 2003;Qian & Boonrucksar 2003;Afşar et al 2004;Lee et al 2004;Yang et al 2004Yang et al , 2007Zhu et al 2004;Borkovits et al 2005;Erdem et al 2007;Pilecki et al 2007;Szalai et al 2007). Systems with independent evidence that the observed (O−C) modulations can be explained by a third body were excluded (actually, it is not possible to exclude the possibility that the observed modulation of some of the systems plotted may still be caused by a third body.…”

Section: A Comparison Of the Observed Orbital Period Modulations Abovmentioning

confidence: 99%

Cyclical period changes in HT Cassiopeiae: a difference between systems above and below the period gap

Baptista

Papadimitriou

Giannakis

2008

A&A

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Aims. We report identification of cyclical changes in the orbital period of the eclipsing cataclysmic variable HT Cas. Methods. We measured new white-dwarf mid-eclipse timings and combined them with published measurements to construct an observed-minus-calculated diagram covering 29 years of observations. Results. The data present a 36 yr period modulation of semi-amplitude ∼40 s, with a statistical significance greater than 99.9 percent with respect to a constant period. Conclusions. We combine our results with those in the literature to revisit the issue of cyclical period changes in cataclysmic variables and their interpretation in terms of a solar-type magnetic activity cycle in the secondary star. A diagram of fractional period change (∆P/P) versus the angular velocity of the active star (Ω) for cataclysmic variables, RS CVn, W UMa, and Algols, reveal that close binaries with periods above the gap (secondaries with convective envelopes) satisfy a relationship ∆P/P ∝ Ω −0.7±0.1 . Cataclysmic variables below the period gap (with fully convective secondaries) deviate from this relationship by more than 3-σ, with average fractional period changes 6 times smaller than those of the systems above the gap.

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Section: A Comparison Of the Observed Orbital Period Modulations Abovmentioning

confidence: 99%

Cyclical period changes in HT Cassiopeiae: a difference between systems above and below the period gap

Baptista

Papadimitriou

Giannakis

2008

A&A

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“…Contact binaries, also known as the W UMa stars, are low‐mass eclipsing binaries consisting of ellipsoidal components with orbital periods less than 1 d, usually in the range 0.2 < P < 0.8 d, with continuously changing brightness (Kang et al 2002; Percy 2007). They consist of solar‐type main‐sequence components which fill their Roche lobes and share a common outer envelope at the inner Lagrangian point.…”

Section: Introductionmentioning

confidence: 99%

Physical parameters of 62 eclipsing binary stars using the All Sky Automated Survey-3 data − I

Deb

Singh

2011

Monthly Notices of the Royal Astronomical Society

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We present a detailed light-curve analysis of publicly available V-band observations of 62 binary stars, mostly contact binaries, obtained by the All Sky Automated Survey (ASAS)-3 project between 2000 and 2009. Eclipsing binaries are important astronomical targets for determining the physical parameters of component stars from the geometry of their orbits. They provide an independent direct method of measuring the radii of stars. We improved the ASAS determined periods and ephemerides, and obtained the Fourier parameters from the phased light curves of these 62 stars. These Fourier parameters were used for preliminary classification of the stars in our sample. The phased light curves were then analysed with the aid of the Wilson-Devinney light-curve modelling technique in order to obtain various geometrical and physical parameters of these binaries. The spectroscopic mass ratios as determined from the radial velocity measurements available in the literature were used as one of the inputs to the light-curve modelling. Thus reliable estimations of parameters of these binaries were obtained with combined photometric and spectroscopic data, and error estimates were made using the heuristic scan method. For several systems in the sample, the solutions were obtained for the first time and would serve as a good source in the future for light-curve analysis based on more precise follow-up CCD photometric observations. Out of 62 stars in the sample, photometric analysis of 39 stars is presented here for the first time using the ASAS photometry and precise spectroscopic mass ratios. From the analysis, we found 54 contact binaries, six semidetached binaries and two detached binaries. The Fourier parameters in the a 2 -a 4 plane were used for preliminary classification, and the final classification was done based on the Roche lobe geometry obtained from the light-curve modelling.

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“…Because our LCs are asymmetric, and the main reason is the variation of spot location and size (Kang et al 2002). Considering this case, cool star-spots model was used to get better solutions.…”

Section: Photometric Solutionsmentioning

confidence: 99%

First photometric study of ultrashort-period contact binary 1SWASP J140533.33+114639.1

Zhang,

Qian,

Michel

et al. 2017

Preprint

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In this paper, CCD photometric light curves for the short-period eclipsing binary 1SWASP J140533.33+114639.1 (hereafter J1405) in the BV R bands are presented and analyzed using the 2013 version of the Wilson-Devinney (W-D) code. It is discovered that the J1405 is a W-subtype shallow contact binary with a contact degree of f = 7.9± 0.5% and a mass ratio of q = 1.55 ± 0.02. In order to explain the asymmetric light curves of the system, a cool star-spot on the more massive component was employed. This shallow contact eclipsing binary may be formed from a short-period detached system through the orbital shrinkage due to angular momentum loss. Based on (O − C) method, the variation of the orbital period was studied using all the available times of the minimum light. The (O − C) diagram reveals that the period is increasing continuously at a rate of dP/dt = +2.09 × 10 −7 days yr −1 , which can be explained by mass transfer from the less massive component to the more massive one.

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Period variation and spot model for the W UMa type binary TY UMa

Cited by 35 publications

References 9 publications

Cyclical period changes in HT Cassiopeiae: a difference between systems above and below the period gap

Cyclical period changes in HT Cassiopeiae: a difference between systems above and below the period gap

Physical parameters of 62 eclipsing binary stars using the All Sky Automated Survey-3 data − I

First photometric study of ultrashort-period contact binary 1SWASP J140533.33+114639.1

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