A Period Study and Light Synthesis for the W Ursae Majoris Type Binary SS Arietis

Kim, Chun-Hwey; Lee, Jae Woo; Han, Wonyong; Koch, Robert de Mello

doi:10.1086/344808

Cited by 29 publications

(18 citation statements)

References 10 publications

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“…In such a case, any secular changes of period by evolutionary effects, such as mass-transfer or massloss, could be suppressed by the dominant cyclic change of the period. Similar cases were found in their period study histories for contact binaries such as YY Eri (Kim 1992, Maceroni & van't Veer 1994, Kim et al 1997 and SS Ari (Kurpinska-Winiarska & Zakrzewski 1990, Demircan & Selam 1993, Kim et al 2003. We thus investigated whether GW Cep fits this case.…”

Section: Period Studysupporting

confidence: 74%

On the Period Change of the Contact Binary GW Cephei

Kim¹,

Song²,

Yoon³

et al. 2010

Journal of Astronomy and Space Sciences

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BVR CCD observations of GW Cep were made on 15 nights in November through December 2008 with a 1-m reflector at the Jincheon station of the Chungbuk National University Observatory. Nineteen new times of minimum lights for GW Cep were determined and added to a collection of all other times of minima available to us. These data were then intensively analyzed, by reference to an O-C diagram, to deduce the general form of period variation for GW Cep. It was found that the O-C diagram could be interpreted as presenting two different forms of period change: an exclusively quasi-sinusoidal change with a period of 32.6 years and an eccentricity of 0.10; and a quasi-sinusoidal change with a period of 46.2 years and an eccentricity of 0.36 superposed on an upward parabola. Although a final conclusion is somewhat premature at present, the latter seems more plausible because late-type contact binaries allow an inter-exchange of both energy and mass between the component stars. The quasi-sinusoidal characteristics were interpreted in terms of a light-time effect due to an unseen tertiary component. The minimum masses of the tertiary component for both cases were calculated to be nearly the same as the 0.23-0.26 M⊙-ranges which is hardly detectable in a light curve synthesis. The upward parabolic O-C diagram corresponding to a secular period increase of about 4.12 × 10 -8 d/yr was interpreted as mass being transferred from the lesser to more massive component. The transfer rate for a conservative case was calculated to be about 2.66 × 10 -8 M⊙/yr which is compatible with other W UMa-type contact binaries.

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Section: Period Studysupporting

confidence: 74%

On the Period Change of the Contact Binary GW Cephei

Kim¹,

Song²,

Yoon³

et al. 2010

Journal of Astronomy and Space Sciences

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“…However, we failed to find any connection between the luminosity variation and the period change. V432 Per is the third of six cool binaries on our program which does not conform to a prediction of Applegate's mechanism (Kim et al 1997(Kim et al , 2003a(Kim et al , 2003bLee et al 2004Lee et al , 2007b. Hence, the sinusoidal component of the period variability most likely arises from the light-time effect due to a dM tertiary companion gravitationally bound to the V432 Per system.…”

Section: Cyclical Period Variationmentioning

confidence: 71%

A Photometric Study of the Short-Period Close Binary V432 Persei and Its Implications for the Star's Evolution

Lee

Youn

Kim

et al. 2008

The Astronomical Journal

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We present new multicolor charge-coupled device (CCD) photometry for the short-period close binary V432 Per, made on six nights between 2006 February and December. A period study of the system, based on all published and newly observed times of minimum light, reveals that the orbital period has varied as a beat effect due to the combination of a secular period increase and a sinusoidal variation, with a period of 35.3 yr and semi-amplitude of 0.0104 d. The continuous period increase can be interpreted as mass transfer from the less massive secondary star to the more massive primary component in the system with a rate of about 1.16 × 10 −7 M yr −1 . The sinusoidal component of the period variability could, in principle, be produced by either a light-time effect due to a third body or a magnetic modulation seated in at least one component star, but light variations do not conform to a prediction of the second mechanism. New light curves, showing a total eclipse at secondary minimum and a variable O'Connell effect, are best modeled by including a third light source and a cool spot on the primary star. The model also represents Agerer's light curves. Our results indicate V432 Per, at present, to be in a broken or a marginal contact stage, investing a hotter, more massive primary star with a spectral type of G4 and a cooler, less massive secondary star with a spectral type of G8−G9. We suggest that the most likely explanation of the sinusoidal variation is the existence of a gravitationally bound M-type tertiary companion. When all of this is verified and understood more comprehensively, the formation and evolution of this binary system should be greatly advanced.

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“…Inserting the values ofṖ , P , M 1 and q into (3), the mass transfer rate can be estimated to be dM 1 /dt = −0.98 × 10 −7 M yr −1 . This kind of period decrease appears in many other weak-contact binaries (i.e., f < 30%), such as SS Ari (Kim et al 2003), TY Boo (Yang et al 2007), UX Eri (Qian et al 2007), RZ Com (He and Qian 2008), BM UMa (Yang et al 2009a), CC Com and BV Dra (Yang et al 2009b), BX Peg (Lee et al 2009), AO Cam and AH Tau (Yang et al 2010). With period decreasing, the inner and outer critical Roche lobes will shrink, and then cause the contact degree to increase.…”

Section: Discussionmentioning

confidence: 94%

First CCD photometry for the contact binary VZ Trianguli

Yang

2009

Astrophys Space Sci

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First CCD photometry is presented for the eclipsing binary VZ Trianguli, observed at the Sheshan Station of Shanghai Astronomical Observatory in 2008. Using the Wilson-Devinney Code, the photometric solution of VZ Tri was first deduced from the R-band observations. The results show that VZ Tri is an A-subtype late-type contact binary, with a mass ratio of q = 0.350(±0.004) and a low contact degree of f = 27.9%(±1.0%). Based on all available light minimum times covering over 40 years, it is found that the orbital period shows a long-term decrease at a rate of dP /dt = −1.52(±0.03) × 10 −7 d yr −1 , suggesting that VZ Tri is undergoing mass transfer from the more massive component to the less massive component, accompanied with angular momentum loss. With period decreasing, the inner and outer critical Roche lobes will shrink, and then cause the contact degree to increase. Therefore, the weak-contact binary VZ Tri with decreasing period may evolve into a deepcontact configuration.

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A Period Study and Light Synthesis for the W Ursae Majoris Type Binary SS Arietis

Cited by 29 publications

References 10 publications

On the Period Change of the Contact Binary GW Cephei

On the Period Change of the Contact Binary GW Cephei

A Photometric Study of the Short-Period Close Binary V432 Persei and Its Implications for the Star's Evolution

First CCD photometry for the contact binary VZ Trianguli

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