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1.
Photometric BVRc observations of the stars CSS J223614+311343, V523 Aur and V783 And were carried out and their absolute parameters (masses, radii and luminosities) were determined based on light curve modeling and Gaia distances. The main results are: (i) The components of CSS J223614+311343 and V783 And are of K spectral type while those of V523 Aur are G stars; (ii) The three systems have middle fillout factors 0.20–0.29; (iii) CSS J223614+311343 and V783 And are of A-subtype while V523 Aur is of W-subtype; (iv) The common target masses are near the lower mass limit for the known W UMa binaries; (v) The smaller in size (and less massive) components of all targets locate above the MS band of the evolutional diagrams while the bigger components are within the MS band. The only exception is the bigger component of V523 Aur that is also above the MS band. This result was attributed to the W-subtype of the target.  相似文献   

2.
We present a new multicolor CCD photometry and light curve analysis of two eclipsing binary systems, 1SWASP J133417.80 + 394314.4 and V2790 Orion. The photometric solutions for both binaries were carried out using the updated version of the Wilson– Devinney code. The results showed that first systems is A- type W UMa with mass ratios q = 0.158 while the second system is W- type with q = 3.2. The systems show over contact configuration with fill-out factors of f = 43% and 14% respectively. We calculated the orbital and absolute physical parameters for both systems and investigated their evolutionary state.  相似文献   

3.
The EW-type eclipsing binaries are strongly interacting systems known to have often both component stars filling their crucial Roche lobes and having a common envelope. We present new BVRI light curves of the eclipsing binaries ZTF J214226.88+435,827.1 (ZTF21+43) and KAO-EGYPT J214216.38+440,015.1 (KAO21+44) based on CCD observations acquired with the 1.88-m Kottamia Astronomical Observatory (KAO) at Newtonian and Cassegrain telescope focus. The modeling results show that these two systems are to be W UMa contact binaries belonging to EW subtypes. All the light curves show the inverse O'Connell effect. We computed new ephemeris for each system using our times of minima and that available in the literature. Using our new times of minima and epochs for both systems from all available observations, the orbital period changes of these structures are studied for our systems. Using the PHOEBE package, a preliminary determination of the two systems' photometric orbital and physical parameters has been present. The positions of the systems were also depicted on the Hertzsprung-Russell (H-R), M-L, and Teff-L diagrams to test their evolutionary status.  相似文献   

4.
The first light curve solutions of the binary systems V1370 Tau and QQ Boo are presented. The periodic changes are calculated, and a new ephemeris presented for each of these two binary systems. O-C analysis is performed using the MCMC method in OCFit code. The changing rate of period was measured as dP/dt= 0.2423 days/year for V1370 Tau and dP/dt= -0.1363 days/year for QQ Boo. The light curve solutions suggest that V1370 Tau is a weak-contact eclipsing binary system with a photometric mass ratio q = 0.829, and that the corresponding fillout factor is 11.06%. Furthermore, it is suggested that the QQ Boo binary system is also a weak-contact W UMa eclipsing binary with a photometric mass ratio q = 0.831, and that its fillout factor equals 10.26%. The light curve solutions require cold spots. Utilizing the Wilson-Devinney code the photometric and geometric parameters of the systems are determined. The distance of both V1370 Tau and QQ Boo are calculated according to the estimated absolute parameters as 159.95 ± 23 pc and 309.03 ± 25 pc, respectively, which are in a good agreement with the distance values derived from the Gaia DR2 parallax within one standard deviation. Moreover, the positions of their components on the H-R diagram are represented.  相似文献   

5.
Photometric observations in Sloan g' and i' bands of four W UMa stars,NSVS 2244206,NSVS908513,CSS J004004.7+385531 and VSX J062624.4+570907,are presented.The light curve solutions reveal that all targets have overcontact configurations with fillout factors within 0.15-0.26.Their components are G-K spectral types and are almost in thermal contact.They are also relatively close in size and luminosity:the radius ratios r_2/r_1 are within 0.75-0.90;the luminosity ratios l_2/l_1 are within 0.53-0.63.The results of the light curve solution of CSS J004004.7+385531 imply the weak limb-darkening effect of its primary component and possible presence of additional absorbing features in the system.  相似文献   

6.
Photometric observations are presented in V and I bands of six eclipsing binaries at the lower limit of the orbital periods for W UMa stars. Three of them are newly discovered eclipsing systems. The light curve solutions reveal that all shortperiod targets are contact or overcontact binaries and six new binaries are added to the family of short-period systems with estimated parameters. Four binaries have components that are equal in size and a mass ratio near 1. The phase variability shown by the V-I colors of all targets may be explained by lower temperatures on their back surfaces than those on their side surfaces. Five systems exhibit the O'Connell effect that can be modeled by cool spots on the side surfaces of their primary components.The light curves of V1067 Her in 2011 and 2012 are fitted by diametrically opposite spots. Applying the criteria for subdivision of W UMa stars to our targets leads to ambiguous results.  相似文献   

7.
With the 2013 version of W-D code, we derived the photometric solutions for the new discovered extremely short-period eclipsing binary 1SWASP J024148.62+372848.3 based on its complete RIc light curves. The results show that the system is a W-type overcontact system with a filling-out factor of 23% and a mass ratio of q = 1.23, thus it is a new target which belongs to the rare group of overcontact binary with period under the short period limit (0.22 days). The obviously asymmetries found in its light curves could be explained well by the high spots coverage on the two components which have strong magnetic activities due to their late type nature. A third light contributing about 40% of the total light has been detected during the light curve analysis. This additional component may play an important role in the formation of 1SWASP J024148.62+372848.3, just like those in other overcontact binaries below the limit.  相似文献   

8.
In a previous paper, using Eggleton's stellar evolution code, we have discussed the structure and evolution of low-mass W Ursae Majoris (W UMa) type contact binaries with angular momentum loss owing to gravitational radiation or magnetic braking. We find that gravitational radiation is almost insignificant for cyclic evolution of low-mass W UMa type systems, and it is possible for angular momentum to be lost from W UMa systems in a magnetic stellar wind. The weaker magnetic activity shown by observations in W UMa systems is likely caused by the lower mass of the convective envelopes in these systems than in similar but non-contact binaries. The spin angular momentum cannot be neglected at any time for W UMa type systems, especially for those with extreme mass ratios. The spin angular momenta of both components are included in this paper and they are found to have a significant influence on the cyclic evolution of W UMa systems. We investigate the influence of the energy transfer on the common convective envelopes of both components in detail. We find that the mass of the convective envelope of the primary in contact evolution is slightly more than that in poor thermal contact evolution, and that the mass of the convective envelope of the secondary in contact evolution is much less than that in poor thermal contact evolution. Meanwhile, the rate of angular momentum loss of W UMa type systems is much lower than that of poor thermal contact systems. This is indeed caused by the lower masses of the convective envelopes of the components in W UMa type systems. Although the models with angular momentum loss for W UMa systems exhibit cyclic evolution, they seem to show that a W UMa system cannot continue this type of cyclic evolution indefinitely, and it might coalesce into a fast-rotating star after about 1200 cycles of evolution (about  7.0 × 109 yr  ).  相似文献   

9.
We present the results of our study of the eclipsing binary systems CSS J112237.1+395219,LINEAR 1286561 and LINEAR 2602707 based on new CCD B, V, Rcand Iccomplete light curves. The ultra-short period nature of these stars, as reported by Drake et al., is confirmed and the system's periods are revised. The light curves were modeled using the 2003 version of the Wilson-Devinney code. When necessary, cool spots on the surface of the primary component were introduced to account for asymmetries in the light curves. As a result, we found that CSS J112237.1+395219 is a W UMa type contact binary system belonging to W subclass with a mass ratio of q = 1.61 and a shallow degree of contact of 14.8%where the primary component is hotter than the secondary one by 500 K. LINEAR 1286561 and LINEAR2602707 are detached binary systems with mass ratios q = 3.467 and q = 0.987 respectively. These detached systems are low-mass M-type eclipsing binaries with similar temperatures. The marginal contact,fill-out factor and temperature difference between components of CSS J112237.1+395219 suggest that this system may be at a key evolutionary state predicted by thermal relaxation oscillation(TRO) theory. From the estimated absolute parameters, we conclude that our systems share common properties with other ultrashort period binaries.  相似文献   

10.
Using the data from the public database of the All Sky Automated Survey (ASAS) we performed the very first light curve analyses of the three eclipsing binary systems AO Aqr, CW Aqr and ASAS 012206-4924.7. The physical parameters of the systems were determined by the PHOEBE (Prša and Zwitter, 2005) software. From an analysis of the ASAS data it was concluded that AO Aqr was found to be a contact binary system while CW Aqr and ASAS 012206-4924.7 were found to be near-contact and detached binaries, respectively. Finally, the locations of the components, corresponding to the estimated physical parameters, in the HR diagram were also discussed.  相似文献   

11.
Photometric observations of four totally-eclipsing W UMa binaries, NSVS 6673994, NSVS 4316778, PP Lac and NSVS 1926064, are presented. Their global parameters were determined from the light curve solutions and GAIA distances. The main results are as follows: (i) NSVS 6673994, NSVS 4316778 and PP Lac are of W subtype while NSVS 1926064 is of A subtype; (ii) The mass ratios of NSVS 4316778 and NSVS 1926064 are close to the lower mass-ratio limit; (iii) NSVS 4316778 has double contact configuration while NSVS 1926064 is in deep contact; (iv) The changes of the PP Lac period seem cyclic and are accompanied with episodes of essentially constant value; (v) The relations between the global parameters of the four W UMa stars differ considerably from those of Main Sequence (MS) stars. The deviations of the radii, temperatures and luminosities of the stellar components from those of MS stars with the same masses are bigger for the two targets with extremely small mass ratio.  相似文献   

12.
本文给出了一个确定大熊W型双星质量比的近似方法。如果知道大熊W型双星的周期P、主子星表面有效温度T_p和主次食深差△m,可通过该文导出的一个公式算得质量比。对21个大熊W双星进行了计算,结果表明用该方法确定的质量比同分光或测光质量比符合较好。  相似文献   

13.
We present the first light curve analysis and modeling for the short period close binary 1SWASP J222514.69 + 361643.0. The results show that the system is in over contact with factor ƒ = 53%. The primary component is the massive and hotter one. The system is A-subtype W UMa eclipsing binary with spectral types K2 and K3, respectively.  相似文献   

14.
With the aim of providing new and up-to-date absolute parameters of some close binary systems, new BVR CCD photometry was carried out at the Ankara University Observatory (AUG) for five eclipsing binaries, ET Boo, V1123 Tau, V1191 Cyg, V1073 Cyg and V357 Peg between April, 2007 and October, 2008. In this paper, we present the orbital solutions for these systems obtained by simultaneous light and radial velocity curve analyses. Extensive orbital solution and absolute parameters for ET Boo system were given for the first time through this study. According to the analyses, ET Boo is a detached binary while the parameters of four remaining systems are consistent with the nature of contact binaries. The evolutionary status of the components of these systems are also discussed by referring to their absolute parameters found in this study.  相似文献   

15.
The common convective envelope model for W UMa systems is used to analyse the light curves of the sixteen systems with spectroscopic mass ratios. From the derived photometric elements, an indication is found that Binnendijk's W-type systems have only shollow common envelopes, which is therefore suggested to be the cause of the difference between A- and W-type systems. It is also suggested that the structure of many contact binaries permits only a shallow common envelope and that further study of such envelopes will yield the modification in the model required if a closer fit to the W-type light curves is to be obtained.The model is also used with mass ratio as an additional photometric element to analyse the light curve of AW UMa. The solution obtained confirms the remarkably small mass ratio of 0.08 found by Mauder and by Mochnacki and Doughty.Originally presented at the IAU Colloquium No. 16 held at the University of Pennsylvania, Philadelphia, Pa., U.S.A., September 8–11, 1971.  相似文献   

16.
Photoelectric BV observations of W UMa-type binaries CK Boo, BI CVn, and AH Vir are presented, and light curve variations and shifts of minima are discussed in the context of stellar activity and mass transfer. The O–C increments in three systems were found to be 0.08, 0.80, and 0.60 s per revolution, respectively. The new ephemeris for the future observations were also found.  相似文献   

17.
A catalog of W UMa type eclipsing binary systems with tertiary components based on eclipse timing diagrams is presented listing the physical and orbital parameters (including third body parameters) of 150 W UMa type eclipsing binaries.In this study, the (O–C) diagrams of nine sample W UMa type eclipsing binary systems, based on the most reliable timings of minima in the literature, are analyzed to obtain the third-body parameters and significant statistical results are presented from the data in the catalog.  相似文献   

18.
The first light curve solutions of the stars EW and HN in the Pisces constellation are presented. Photometry, and its’ periodic changes are calculated and discussed. The analysis of the O-C diagram is done by the MCMC approach in the OCFit code and a new ephemeris is provided for the two binary systems. The results show that EW Psc is a near contact eclipsing binary system with a photometric mass ratio q = 0.587, and the fillout factor is -0.034 and -0.018 for the primary and secondary components, respectively. The solution results also show that the system HN Psc is a weak-contact W UMa eclipsing binary with a photometric mass ratio q = 0.853, and with a fillout factor of 5.6%. The light curves solutions required a cold spot to account for the O'Connell effect.  相似文献   

19.
We present the first light curve analysis for two newly discovered W UMa eclipsing binaries in the field of the globular cluster M15. As spectroscopic observations are not available, we used the FOTEL program to obtain the light curve solution of both systems. The fundamental properties of each system are obtained. Several tests concerning values of mass ratio and effective temperatures were carried out. Independent distance moduli for each system are obtained, and the membership to the parent cluster is discussed. It is shown that W2 is a member of M15, whereas W1 is not.  相似文献   

20.
We present photometric analysis of 8 short-period eclipsing binaries discovered and observed at Astronomical Observatory at Kolonica Saddle between 2007 and 2010 with different instruments. We determined their orbital periods and performed photometric analysis of their light curves. We found that 3 systems are detached binaries, 4 systems are over-contact binaries of W UMa type and one system is semi-detached with the secondary component filling its Roche lobe. Light curves of 2 systems exhibit asymmetries, explained by spot(s) on the surface of the components.  相似文献   

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