Accurate integrations of the Roche model

Mochnacki, S. W.

doi:10.1086/190967

Cited by 96 publications

(84 citation statements)

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“…The distance between the first Lagrange point and the center of mass which which enter H P and Q are interpolated from the tables of Kopal (1978) and Mochnacki (1984). We note that this treatment is only correct for stars with small photospheric pressure scale compared to their radius (Pastetter & Ritter 1989).…”

Section: Methodsmentioning

confidence: 99%

Formation of contact in massive close binaries

Wellstein

Langer

Braun

2001

A&A

402

666

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Abstract. We present evolutionary calculations for 74 close binaries systems with initial primary masses in the range 12...25 M , and initial secondary masses between 6 and 24 M . The initial periods were chosen such that mass overflow starts during the core hydrogen burning phase of the primary (Case A), or shortly thereafter (Case B). We use a newly developed binary code with up-to-date physics input. Of particular relevance is the use of OPAL opacities, and the time-dependent treatment of semiconvective and thermohaline mixing. We assume conservative evolution for contact-free systems, i.e., no mass or angular momentum loss from those system except due to stellar winds. We investigate the borderline between contact-free evolution and contact, as a function of the initial system parameters. The fraction of the parameter space where binaries may evolve while avoiding contact -which we found already small for the least massive systems considered -becomes even smaller for larger initial primary masses. At the upper end of the considered mass range, no contact-free Case B systems exist. While for primary masses of 16 M and higher the Case A systems dominate the contact-free range, at primary masses of 12 M contact-free systems are more frequent for Case B. We identify the drop of the exponent x in the main sequence mass-luminosity relation of the form L ∝ M x as the main cause for this behaviour. For systems which evolve into contact, we find that this can occur for distinctively different reasons. While Case A systems are prone to contact due to reverse mass transfer during or after the primary's main sequence phase, all systems obtain contact for initial mass ratios below ∼ 0.65, with a merger as the likely outcome. We also investigate the effect of the treatment of convection, and found it relevant for contact and supernova order in Case A systems, particularly for the highest considered masses. For Case B systems we find contact for initial periods above ∼ 10 d. However, in that case (and for not too large periods) contact occurs only after the mass ratio has been reversed, due to the increased fraction of the donor's convective envelope. As most of the mass transfer occurs conservatively before contact is established, this delayed contact is estimated to yield to the ejection of only a fraction of the donor star's envelope. Our models yield the value of β, i.e., the fraction of the primaries envelope which is accreted by the secondary. We derive the observable properties of our systems after the major mass transfer event, where the mass gainer is a main sequence or supergiant O or early B type star, and the mass loser is a helium star. We point out that the assumption of conservative evolution for contact-free systems could be tested by finding helium star companions to O stars. Those are also predicted by non-conservative models, but with different periods and mass ratios. We describe strategies for increasing the probability to find helium star companions in observational search programs.

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Section: Methodsmentioning

confidence: 99%

Formation of contact in massive close binaries

Wellstein

Langer

Braun

2001

A&A

402

666

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“…Filling factors F (see e.g. Mochnacki 1984) are between 0.91 and 0.97 for the primary, and between 0.84 and 0.72 for the secondary. Formally, the best solutions correspond to a mass ratio of around 1.2, which is, however, not very likely.…”

Section: Light Curve Analysis Photometric Elementsmentioning

confidence: 99%

Eclipsing binaries in the Magellanic Clouds

Clausen¹,

Storm

Larsen

et al. 2003

A&A

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Abstract. We present new accurate CCD uvby light curves for the LMC eclipsing binaries HV 982 and HV 12578, and for the SMC systems HV 1433 and HV 11284 obtained at the Danish 1.5 m telescope at ESO, La Silla. The light curves were derived from DoPHOT photometry, and typical accuracies are between 0.007 and 0.012 mag per point. Standard uvby indices have also been established for each binary, primarily for determination of interstellar reddening and absorption. For HV 982 and HV 12578, accurate photometric elements have been established. Both systems consist of two detached components of comparable sizes in an eccentric orbit. Adopting the spectroscopic elements given by Fitzpatrick et al. (2002) for HV 982, we derive absolute dimensions of its components which agree well with their results. A distance modulus of V 0 − M V = 18.63±0.08 is obtained, corresponding to a distance of 53.2± 2.0 kpc, which is in formal agreement with (although slightly larger than) their determination. HV 1433 and HV 11284 both consist of two rather close, deformed and quite different stars. As the mass ratios between the components (and their rotation rates) are not known, definitive photometric elements can not yet be obtained, but we present a sample of possible photometric solutions. In a series of forthcoming papers we will combine our uvby observations with high-dispersion spectra from the UVES spectrograph on the ESO Very Large Telescope (VLT) and present absolute dimensions, chemical abundances and distances for selected LMC and SMC systems, including HV 12578 and refined results for HV 982.

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“…The absolute dimensions for KIC 6220497 can be computed from our photometric solutions and M1. These are given in the bottom of Table 1, where the radii are the mean volume radii calculated from the tables of Mochnacki (1984). The luminosities and the bolometric magnitudes were computed by adopting T eff ⊙=5,780 K and M bol⊙ =+4.73 for solar values.…”

Section: Kepler Photometry and Light-curve Synthesismentioning

confidence: 99%

KIC 6220497: a new Algol-type eclipsing binary with multiperiodic pulsations

Lee¹,

Hong²,

Koo³

2016

Mon. Not. R. Astron. Soc.

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We present both binarity and pulsation of KIC 6220497 from the Kepler observations. The light curve synthesis shows that the eclipsing system is a semi-detached Algol with parameters of q = 0.243±0.001, i = 77.3±0.3 deg, and ∆T = 3,372±58 K, in which the detached primary component fills its Roche lobe by ∼87%. A multiple frequency analysis of the eclipse-subtracted light residuals reveals 33 frequencies in the range of 0.75−20.22 d −1 with amplitudes between 0.27 and 4.56 mmag. Among these, four are pulsation frequencies in fundamental (f 1 , f 5 ) and p (f 2 , f 7 ) modes, and six are orbital frequency (f 8 , f 31 ) and its harmonics (f 6 , f 11 , f 20 , f 24 ), which can be attributed to tidally excited modes. For the pulsation frequencies, the pulsation constants of 0.16−0.33 d and the period ratios of P pul /P orb = 0.042−0.089 indicate that the primary component is a δ Sct pulsating star and, thus, KIC 6220497 is an oscillating eclipsing Algol (oEA) star. The dominant pulsation period of 0.1174051±0.0000004 d is significantly longer than that expected from empirical relations that link the pulsation period with the orbital period. The surface gravity of log g 1 = 3.78±0.03 is clearly smaller than those of the other oEA stars with similar orbital periods. The pulsation period and the surface gravity of the pulsating primary demonstrate that KIC 6220497 would be the more evolved EB, compared with normal oEA stars.

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Accurate integrations of the Roche model

Cited by 96 publications

References 0 publications

Formation of contact in massive close binaries

Formation of contact in massive close binaries

Eclipsing binaries in the Magellanic Clouds

KIC 6220497: a new Algol-type eclipsing binary with multiperiodic pulsations

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