Two very similar late-type contact systems - BX and BB Pegasi

Leung, K. C.; Zhai, D. S.; Zhang, Y.

doi:10.1086/113759

Cited by 8 publications

(7 citation statements)

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“…As listed in Table 7, our photometric solutions for the new light curves are quite consistent with those of Leung et al (1985) and Samec & Hube (1991), except for the fill‐out factor. Our fill‐out factor is 12 per cent and 4 per cent larger than those of Leung et al and Samec & Hube, respectively.…”

Section: Light Variation and Light‐curve Synthesissupporting

confidence: 69%

“…The individual observations of Zhai & Zhang (1979) still have not become available. Therefore, the normal points with standardized magnitudes published by Leung et al (1985) were used. To calculate their Δ y and Δ( b − y ) at the appropriate phases, the standardized normal points were subtracted from standard magnitudes and colour indices [ V = 10.65, ( B − V ) = 1.13] of the comparison star measured by Samec (1990).…”

Section: Period Variabilitymentioning

confidence: 99%

“…The new light curves were subjected to a differential correction procedure with the WD98 code (R. E. Wilson, private communication). The reader should note that we are using the numerical subscripting of Leung et al (1985) and not the opposite notation of the other authors. After adopting the light curves of 1999 as reference ones, we modelled those of 2000 by adjusting only the orbital ephemeris ( T 0 and P ), the spot and the luminosity parameters.…”

Section: Light Variation and Light‐curve Synthesismentioning

confidence: 99%

“…Kaluzny (1984) reanalysed Hoffmann's yellow light curve using code from Rucinski (1976) and concluded that the binary is a contact system with q = 2.70, i = 87.8° and a fill‐out factor f = 16 per cent. Leung, Zhai & Zhang (1985) used the Wilson & Devinney (1971, hereafter WD) code to solve the Zhai & Zhang (1979) BV light curves. They found a photometric solution similar to that of Kaluzny with the results: q = 2.80, i = 88.4° and f = 11 per cent.…”

Section: Introductionmentioning

confidence: 99%

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Period and light variations for the cool, overcontact binary BX Pegasi

Lee

Kim

Han

et al. 2004

Monthly Notices of the Royal Astronomical Society

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New charge-coupled device photometric observations of the W UMa-type binary BX Pegasi (BX Peg) were collected on four nights from 1999 October to 2000 September. The light curve was covered completely in each season. Seven new times of minimum light were determined. It was found that the orbital period of the system has varied recently in a sinusoidal way, superimposed on a downward parabolic variation. The long-term period decrease rate is deduced as dP/dt = −8.62 or 9.59 × 10 −8 d yr −1 , which can be interpreted as either mass transfer from the more massive cool star to the less massive hot component, or as the combination of mass transfer and angular momentum loss due to a magnetic stellar wind. The period and amplitude of the sinusoidal period variation were calculated to be about 35.3 yr and 0.015 d, respectively. The light curves of BX Peg are asymmetric and show year-to-year light variability. A spot model has been applied to analyse these light curves. After using the light curves of 1999 as reference ones, we solve those of 2000 by adjusting only the spot parameters. One cool-spot model on the cool secondary satisfies the observed light curves of both 1999 and 2000 quite well and shows a good representation of the BX Peg system for both the photospheric and spot descriptions. The brightness variations of BX Peg are not coincident with the period variations and so do not conform to a prediction of the Applegate mechanism. We think the most likely cause of the cyclical variation is the light-time effect due to a third body, although no third light was detected in the light-curve analysis. If it exists, the hypothetical object could be a very red main-sequence star or a white dwarf. We have solved anew the historical published light curve for only the spot parameters and these closely resemble our spot parameters. We speculate that this result is associated with the small coronal saturation of the cool star of the system.

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Section: Light Variation and Light‐curve Synthesissupporting

confidence: 69%

Section: Period Variabilitymentioning

confidence: 99%

Section: Light Variation and Light‐curve Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Period and light variations for the cool, overcontact binary BX Pegasi

Lee

Kim

Han

et al. 2004

Monthly Notices of the Royal Astronomical Society

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“…The results of the different light curve solution models (M) have been denoted by different numbers. It has been assigned M1 in Table 4 to two colors (B and V), light curves solution obtained from Cerruti-Sola & Scaltriti (1980), M2 to two colors (B and V) light curves model of (the mean values are taken from Leung et al 1985), M3 to three colors (U, B, and V) light curves that were obtained by Awadalla (1988) and, M4 to two color (R and V) light curves obtained in this study. All the results appear to be compatible with each other.…”

Section: Light Curve Analysismentioning

confidence: 99%

Absolute Properties of the Binary System BB Pegasi

et al. 2007

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We present a ground based photometry of the low-temperature contact binary BB Peg. We collected all times of mid-eclipses available in literature and combined them with those obtained in this study. Analyses of the data indicate a period increase of 3.0(1) × 10 −8 days/yr. This period increase of BB Peg can be interpreted in terms of the mass transfer 2.4×10 −8 M ⊙ yr −1 from the less massive to the more massive component. The physical parameters have been determined as M c = 1.42 M ⊙ , M h = 0.53 M ⊙ , R c = 1.29 R ⊙ , R h = 0.83 R ⊙ , L c = 1.86 L ⊙ , and L h = 0.94 L ⊙ through simultaneous solution of light and of the radial velocity curves. The orbital parameters of the third body, that orbits the contact system in an eccentric orbit, were obtained from the period variation analysis. The system is compared to the similar binaries in the Hertzsprung-Russell and Mass-Radius diagram.

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Synthesis Methods for Eclipsing-Binary Light Curves

Etzel

Leung

1990

Active Close Binaries

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Two very similar late-type contact systems - BX and BB Pegasi

Cited by 8 publications

References 0 publications

Period and light variations for the cool, overcontact binary BX Pegasi

Period and light variations for the cool, overcontact binary BX Pegasi

Absolute Properties of the Binary System BB Pegasi

Synthesis Methods for Eclipsing-Binary Light Curves

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