A Period Study of the Eclipsing Binary U Sagittae

Manzoori, Davood; Gozaliasl, G.

doi:10.1086/511064

Cited by 10 publications

(13 citation statements)

References 27 publications

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“…Manzoori & Gozaliazl (2007) have determined a value forṖ (thusṀ) and have seen a hot spot on the gainer's surface for which a range of temperatures is given by Richards & Albright (1999). A value for L add has been determined by Albright & Richards (1996), which makes this binary a well-described system.…”

Section: Discussionmentioning

confidence: 99%

Mass loss out of close binaries

Rensbergen

Greve

Mennekens

et al. 2011

A&A

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Context. Several authors have previously introduced liberal evolution of interacting binaries, with the purpose of meeting various observed binary characteristics better than with conservative evolution. Since Algols are eclipsing binaries, the distribution of their orbital periods is known precisely. The distribution of their mass ratios contains, however, more uncertainties. We try to reproduce these two distributions theoretically using a liberal scenario in which the gainer star can lose mass into interstellar space as a consequence of its rapid rotation and the energy of a hot spot. Aims. In a recent paper we calculated the liberal evolution of binaries with a B-type primary at birth where mass transfer starts during core hydrogen burning of the donor. In this paper we include the cases where mass transfer starts during shell hydrogen burning, and it is our aim to reproduce the observed distributions of the system parameters of Algol-type semidetached systems. Methods. Our calculations reveal the amount of time that an Algol binary lives with a well-defined value of mass ratio and orbital period. We used these data to simulate the distribution of mass ratios and orbital periods of Algols. Results. Binaries with a late B-type initial primary hardly lose any mass, whereas those with an early B primary evolve in a nonconservative way. Conservative binary evolution predicts only ∼12% of Algols with a mass ratio q above 0.4. This value is raised up to ∼17% using our scenario of liberal evolution, which is still far below the ∼45% that is observed. Conclusions. Observed orbital periods of Algol binaries longer than one day are faithfully reproduced by our liberal scenario. Mass ratios are reproduced better than with conservative evolution, but the resemblance is still poor.

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Section: Discussionmentioning

confidence: 99%

Mass loss out of close binaries

Rensbergen

Greve

Mennekens

et al. 2011

A&A

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“…Manzoori & Gozaliazl (2007) have determined a masstransfer-rate of 1.79×10 −6 M y . A hot spot with a temperature in the range [20 000-100 000] K has been seen by Richards & Albright (1999).…”

Section: U Sgementioning

confidence: 99%

Spin-up and hot spots can drive mass out of a binary

Greve¹,

Loore²,

Mennekens³

2008

A&A

100

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Context. The observed distribution of orbital periods of Algols with a B-type primary at birth agrees fairly well with the prediction from conservative theory. Conservative evolution fails, however, to produce the rather large fraction of Algols observed with a high mass-ratio, especially: q ∈ [0.4-0.6]. Aims. In order to keep Algols for a longer time with a higher mass-ratio without disturbing the distribution of orbital periods too much, interacting binaries have to lose a significant fraction of their total mass without losing much angular momentum before or during Algolism. We propose a mechanism that meets both requirements. Methods. In the case of direct impact the gainer spins up: sometimes up to critical velocity. Equatorial material on the gainer is therefore less bound. A similar statement applies to material located at the edge of an accretion disc. The incoming material moreover creates a hot spot in the area of impact. The sum of the rotational and radiative energy of hot spot material depends on the masstransfer-rate. The sum of both energies overcomes the binding energy at a well defined critical value of the mass-transfer-rate. As long as the transfer-rate is smaller than this critical value RLOF happens conservatively. But as soon as the critical rate is exceeded the gainer will acquire no more than the critical value and RLOF runs into a liberal era. Results. Low-mass binaries never achieve mass-transfer-rates larger than the critical value. Intermediate-mass binaries evolve mainly conservatively but mass will be blown away from the system during the short era of rapid mass-transfer soon after the onset of RLOF. We have calculated the evolution of binaries with a 9 M primary and a 5.4 M companion over a range of initial orbital periods, covering case-A RLOF. Mass-loss from the system is achieved during direct impact only. Conclusions. We find systems that show Algolism for more than ten million years. RLOF occurs almost always conservatively. Only during some 20 000 years the gainer is not capable of grasping all the material that comes from the donor. The mass-ratio q ∈ [0.4-0.6] which was hardly populated by conservative evolution now contains Algols for a significant fraction of their existence.

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“…Though apsidal motion can not be ruled out in this system, the findings of this paper do not support it. For apsidal motion not only a strictly periodic and eccentric orbit is required (which is not the case in this system), but also the O -C residuals for the primary and secondary should be in complete antiphase (see Manzoori & Ghozaliasl 2007). The eccentricity calculated from the observed data is rather low, i.e., 0.001.…”

Section: Causes Of the Cyclic Period Changementioning

confidence: 88%

“…On the other hand, the sine term (the middle panel of Fig. 3) indicates some alternating phenomena modulating the orbital period of the TW And system (see Manzoori 2007).…”

Section: Analysis Of the Period Variations Of Tw Andmentioning

confidence: 99%

“…Additionally, the length of the obtained cyclic period seems to be too long as to be interpreted as a magnetic activity cycle. For example, this period for the sun is 11 yr, for U Sge 9.5 yr (Manzoori 2007), for U Cep 16.4 yr (Manzoori 2008), for Algol 32 yr (Soderhjelm 1980), for UV Leo 24.3 yr (Manzoori 2012a), for SW Cyg 27.9 yr (Manzoori 2007), for RT And 11.9 yr (Manzoori 2009), for EP And 11.72 yr (Manzoori 2012b). …”

Section: Magnetic Activity Cyclementioning

confidence: 99%

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Light and period study of the ecipsing binary system TW Andromedae

Manzoori

2014

Astron Nachr

Self Cite

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Photoelectric light curve (LC) solutions of the close binary system TW And were obtained using the PHOEBE program (version 0.31a). Absolute parameters of the stellar components were then determined, enabling us to discuss the structure and evolutionary status of TW And. The configuration of the system based on the LCs solutions indicates that the secondary component is slightly detached from its critical Roche surface. In addition, times of minima data ("O -C curve") were analyzed. Apart from an almost parabolic variation of the general trend of the O -C data, indicative of a secular increase in the orbital period with a rate 0.032 s yr −1 , which was attributed to a mass transfer with a rate of Δm2 = −1.10×10−10 M yr −1 . Additionally, a sinusoidal variation with a period of 52.75 ± 1.80 yr, modulating the orbital period, was found, which we attribute to a third body orbiting the system.

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A Period Study of the Eclipsing Binary U Sagittae

Cited by 10 publications

References 27 publications

Mass loss out of close binaries

Mass loss out of close binaries

Spin-up and hot spots can drive mass out of a binary

Light and period study of the ecipsing binary system TW Andromedae

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