A Photometric Study of the Near Contact Binary UU Lyncis

Zhu, L.-Y.; Qian, S.‐B.; Soonthornthum, Boonrucksar; He, Jiajia; Yuan, Jianfeng

doi:10.1088/1009-9271/7/2/09

Cited by 11 publications

(6 citation statements)

References 19 publications

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“…The secular period decrease may indicate that the components of WZ Cephei have evolved from a detached configuration to the present marginal state via a primary-to-secondary mass transfer and/or long-time AML, and it will evolve into a normal overcontact system. The situation of WZ Cephei resembles those of VW Boo (Qian & Zhu 2002), UU Lyn (Zhu et al 2007), and II Per ). All have a marginal contact configuration showing a secular decreasing period.…”

Section: Discussionmentioning

confidence: 69%

Wz Cephei: A Close Binary at the Beginning of Contact Phase

Zhu

Qian

2009

The Astronomical Journal

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Photometric photoelectric data of the short-period close binary system, WZ Cephei, are presented. A new photometric analysis with the 2003 version of the Wilson-Devinney method confirmed that it is a shallow contact binary (f ∼ 13.3%) with a high level of spot activity on the primary component. Combining new determined times of light minimum with the others published in the literature, the period change of the binary star is investigated. A periodic variation, with a period of 34.2 years and an amplitude of 0.d 013, was discovered to be superimposed on a long-term period decrease (dP/dt = −8.8 × 10−8 days year −1 ). Both the secular period decrease and the shallow contact configuration suggest that this binary system is at the beginning of contact phase. It is on the way to evolving into a normal overcontact phase via secular angular momentum loss and/or mass transfer from the more massive component to the less massive one. The period oscillation can be explained either by the light-time effect due to the presence of a third body or by magnetic activity. On the one hand, if it is caused by the light-time effect, the mass and the orbital radius of the additional body should be m 3 = 0.17 M and a 3 = 26.6 AU, respectively, when this body is coplanar to the orbit of the eclipsing pair. On the other hand, since the system shows high levels of spot activity, the period oscillation may be explained as a consequence of magnetic cycles. In this case, the required variation of the quadrupole moment is calculated to be 9.2 × 10 49 g cm 2 .

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Section: Discussionmentioning

confidence: 69%

Wz Cephei: A Close Binary at the Beginning of Contact Phase

Zhu

Qian

2009

The Astronomical Journal

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“…The detection of J1744 as an EB-type binary with an orbital shorter than 0.4 d (0.3781 d) makes it an interesting system. It resembles UU Lyn (Zhu et al 2007), II Per (Zhu et al 2009), and 4.71321 × 10 −4 2.91117 × 10 −4 a These were obtained by the method described in Section 4. b f = (Ωstar − Ω inner )/(Ωouter − Ω inner ), where Ω inner , Ωouter and Ωstar are the modified dimensionless potential of inner Roche lobe, outer Roche lobe and star surface, respectively. c The theoretical mean densities M/( 4 3 R 3 ) in solar unit of 1410.040 842 kg m −3 , which were derived from photometric solutions (Zhang et al 2017).…”

Section: Discussionmentioning

confidence: 99%

ASAS J174406+2446.8 is identified as a marginal-contact binary with a possible cool third body

Shi

Qian

Lin-Jia

et al. 2020

Res. Astron. Astrophys.

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ASAS J174406+2446.8 was originally found as a δ Scuti-type pulsating star with the period P = 0.189068 d by ASAS survey. However, the LAMOST stellar parameters reveal that it is far beyond the red edge of pulsational instability strip on the log g − T diagram of δ Scuti pulsating stars. To understand the physical properties of the variable star, we observed it by the 1.0-m Cassegrain reflecting telescope at Yunnan Observatories. Multi-color light curves in B, V, Rc and Ic bands were obtained and are analyzed by using the W-D program. It is found that this variable star is a shallow-contact binary with an EB-type light curve and an orbital period of 0.3781 d rather than a δ Scuti star. It is a W-subtype contact binary with a mass ratio of 1.135(± 0.019) and a fill-out factor of 10.4%(± 5.6)%. The situation of ASAS J174406+2446.8 resembles those of other EB-type marginal-contact binaries such as UU Lyn, II Per and GW Tau. All of them are at a key evolutionary phase from a semi-detached configuration to a contact system predicted by the thermal relaxation oscillation theory. The linear ephemeris was corrected by using 303 new determined times of light minimum. It is detected that the O – C curve shows a sinusoidal variation that could be explained by the light-travel-time effect via the presence of a cool red dwarf. The present investigation reveals that some of the δ Scuti-type stars beyond the red edge of pulsating instability strip on the log g – T diagram are misclassified eclipsing binaries. To understand their structures and evolutionary states, more studies are required in the future.

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“…In this case, the binary will evolve into a "brokencontact" configuration as predicted by the thermal relaxation model (Webbink 2003). Therefore, IU Cnct provides more good observational evidence supporting the thermal relaxation oscillation model (TRO; Webbink 2003), and resembles other binaries, such as DD Com (Zhu et al 2010), II Per (Zhu et al 2009), RV Psc (He & Qian 2009) and UU Lyn (Zhu et al 2007).…”

Section: Discussionmentioning

confidence: 63%

IU Cancri: a solar-type contact binary with mass transfer

Yuan

Dai

Yang

2019

Res. Astron. Astrophys.

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We present new CCD photometry of the solar-type contact binary IU Cnc, which is observed from 2017 November to 2018 March with three small telescopes in China. BV light curves imply that IU Cnc is a W-type contact binary with total eclipses. Photometric solution indicates that the mass ratio and fill-out factor are q = 4.104±0.004 and f = 30.2 ± 0.3%, respectively. From all available light minimum times, the orbital period may increase at a rate of dP/dt = +6.93(4)×10 −7 d yr −1 , which may result from mass transfer from the secondary component to the primary one. With mass transferring, IU Cnc may evolve from a contact configuration into a semi-detached configuration.

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A Photometric Study of the Near Contact Binary UU Lyncis

Cited by 11 publications

References 19 publications

Wz Cephei: A Close Binary at the Beginning of Contact Phase

Wz Cephei: A Close Binary at the Beginning of Contact Phase

ASAS J174406+2446.8 is identified as a marginal-contact binary with a possible cool third body

IU Cancri: a solar-type contact binary with mass transfer

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