Period variation of the W UMa-type binary UZ Leonis

Hegedüs, T.; Jäger, Zoltán

doi:10.1086/133045

Cited by 11 publications

(13 citation statements)

References 12 publications

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“…The quadratic term value is in agreement with that published by Hegedus & Jager (1992). A possible explanation for the (O–C) shape would be either mass transfer between the components as suggested by Hegedus & Jager (1992) or that, at this time, we see just part of a larger, cyclic curve due to a third body orbiting the contact system on a wide orbit. Our light‐curve solution might support the latter explanation: the resulting third light contribution is significant, reaching almost 14 per cent in the B filter.…”

Section: Discussion Of Results and Conclusionsupporting

confidence: 90%

“…Photoelectric observations from Binnendijk (1972) and Kaitchuck (1979) show smooth light curves, typical of a contact binary with total eclipses. Hegedus & Jager (1992) published a complete light curve in the V band and precise times of minima. Their (O–C) study resulted with the first estimation of the period increase rate [a quadratic term in the (O–C) fitting], which was suggested to be the result of mass transfer from the less massive to the more massive component.…”

Section: Introductionmentioning

confidence: 99%

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Physical parameters of components in close binary systems - VII

Zoła

Gazeas

Kreiner

et al. 2010

Monthly Notices of the Royal Astronomical Society

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We present results of the modelling of multicolour light curves of 10 contact binary systems: V376 And, V523 Cas, CC Com, BX Dra, FG Hya, UZ Leo, XY Leo, AM Leo, EX Leo and RT LMi. The solutions resulted in a contact configuration for all systems. We found only FG Hya and UZ Leo to be in deep contact, the latter almost filling the outer critical lobe. The absolute parameters of the components have been determined with an accuracy of about a few per cent based on combined photometric and radial velocity curves, enlarging the sample of systems to 58 for which the physical parameters have been obtained in a uniform way. All but three systems (BX Dra, AM Leo and RT LMi) show asymmetries and peculiarities in the observed light curves, interpreted as resulting from their magnetic activity.

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Section: Discussion Of Results and Conclusionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Physical parameters of components in close binary systems - VII

Zoła

Gazeas

Kreiner

et al. 2010

Monthly Notices of the Royal Astronomical Society

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“…Here we must point out a serious difficulty in determining the mass ratio photometrically when there are several significantly different values of q which reproduce the observed light curve equally satisfactorily as, for example, with FZ Ori q can vary from 0.2 to 0.9 [80,111] and UZ Leo, from 0.12 to 0.7 [69]. The difference in the spectroscopic and photometric mass ratios for the W UMa class has been studied by Pribulla et al [30] for a sample of 92 stars and a tertiary brightness that reduces the depth of the minima, the presence of gas in the system, and low quality photographic spectra were indicated as possible causes.…”

Section: Secular Variation In P Orbmentioning

confidence: 99%

Variation in the orbital period of W UMa-type contact systems

Dryomova¹,

Свечников²

2006

Astrophysics

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The secular variation in the orbital period P orb is studied as a function of the mass ratio q of the components in a sample of 73 contact systems of class W UMa constructed from a survey of current (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003) published photometric and spectroscopic data. Almost all the W UMa-systems (>93% of this sample) are found to have a variation in their orbital periods P orb which alternates in sign independently of their division into A-and Wsubclasses. A statistical study of this sample in terms of the observed characteristics dP orb /dt and q showed that on the average the numbers of increases (35 systems) and decreases (33 systems) in the periods are the same, which indicates the existence of flows directed alternately from one component to the other and illustrates the cyclical character of the thermal oscillations. An analysis of the behavior of dP orb /dt as a function of the mass interval of the primary component yields a more accurate value for the mass ratio,at which contact binaries are separated into A-and W-subclasses. No correlations were observed between the fill-out factor for the outer contact configuration, the total mass of the contact system, and the mass ratio of the components, on one hand, and the sign of the secular variation in the period. The physical properties and evolutionary features of these systems are discussed.

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“…The details of Applegate's mechanism have been studied by Lanza et al (1998). They pointed out that apart from redistribution of the Zhai & Huang 1980;(6) Samec et al 1998; (7) Hegedus & Jager 1992;(8) Wolf & Molík 1996;(9) Herczeg 1993;(10) Qian 2001b;(11) Samec 1990;(12) Kim et al 1997;(13) Zhang et al 1989;(14) Borkovits & Hegedues 1996;(15) Pribulla et al 1999a;(16) Molík & Wolf 1998;(17) Kaszas et al 1998; (18) internal angular velocity, the change in the azimuthal field intensity can also produce a change in the oblateness of the active component. The connection between models of orbital period modulation and extant models of the generation of magnetic fields in stars with interior convection zones was also discussed by Lanza et al (1998).…”

Section: Possible Explanation Of Period Changementioning

confidence: 99%

Period Changes of Two W UMa–Type Contact Binaries: RW Comae Berenices and CC Comae Berenices

Yang¹,

Liu²

2003

PUBL ASTRON SOC PAC

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ABSTRACT.From the present times of minimum light and those collected from the literature, changes in the orbital period of the two W UMa-type contact binaries RW Com and CC Com are analyzed. The results reveal that the period changes of these two systems show the same natures, with a short-term oscillation superposed on the secular decrease. For RW Com, its period shows a secular decrease at a rate of Ϫ7 dP/dt p 0.43 # 10 days yrϪ1 . An oscillation with a periodicity of 13.7 yr and an amplitude of days is superposed Ϫ7 DP p 5.4 # 10 on the secular decrease. For CC Com, its period shows a secular decrease at a rate of days Ϫ7 dP/dt p 0.40 # 10 yrϪ1 . An oscillation with a periodicity of 16.1 yr and an amplitude of days is superposed on Ϫ7 DP p 2.8 # 10 the secular decrease. The period secular decreases of the two systems may be explained by a mass-transfer rate of for RW Com and for CC Com. The periodshort-term oscillations of the two systems may be explained by the magnetic activity cycle model given by Applegate, and the parameters for the magnetic activity cycle model are presented.

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Period variation of the W UMa-type binary UZ Leonis

Cited by 11 publications

References 12 publications

Physical parameters of components in close binary systems - VII

Physical parameters of components in close binary systems - VII

Variation in the orbital period of W UMa-type contact systems

Period Changes of Two W UMa–Type Contact Binaries: RW Comae Berenices and CC Comae Berenices

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