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1.
Several eclipsing binary systems have been selected for combined spectral and photometric observations using the Bulgarian NAO 2 m telescope and several smaller telescopes located at various places in the CESE region. Preliminary results, based on a pilot study started in 2001, about radial velocity and light curve variations of the active W UMa system LS Del are presented here.  相似文献   

2.
A new method for the determination of the proximity effects and gravity darkening exponents in contact binaries of W UMa type is presented. The method is based on Kopal’s method of Fourier analysis of the light changes of eclipsing variables in the Frequency Domain. The method was applied to 36 W UMa systems for which geometric and photometric elements have been derived by the most powerful techniques. The derived values are very close to those predicted by the existing theory of radiative transfer or convective equilibrium.  相似文献   

3.
Two-colour photoelectric observations of the new eclipsing binary HD 199497 are presented. Our observations confirm that the system is a W UMa type eclipsing binary. The light curves were analysed with the Wilson-Devinney approach. The system is found to be in contact configuration. The inclination is amazingly small. Although there are no spectroscopic data, the photometric mass ratio of the system is well determined.  相似文献   

4.
Photometric analysis of BVR C light curves of newly discovered eclipsing binary GSC 0008-00901 is presented. The orbital period is improved to 0.28948(11) days. Photometric parameters are determined as well. The analysis yielded to conclusion that system is an over-contact binary of W UMa type with components not in thermal contact. The light curves from 2005 show the presence of a spot on the surface of one of the components, while light curves from 2006 are not affected by maculation.  相似文献   

5.
New ground-based BV RI CCD observations of the eclipsing binary systems NN Vir and YY CrB are analyzed and illustrated. New times of minima are given and new ephemerides are proposed. The light curves are analyzed with the Wilson-Devinney light curve synthesis code and new geometric and photometric elements are derived. These elements are used together with the available spectroscopic data to compute absolute elements. The evolutionary status of each system is studied by means of mass-radius diagrams. The systems NN Vir and YY CrB are found to be A-type and W-type W UMa systems, respectively.  相似文献   

6.
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   

7.
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   

8.
Photoelectric light curves of V1022 Oph inB andV are presented. It has been confirmed that it is a W UMa type eclipsing binary with one of the shortest periods known (P<0.d25). Some general properties of the system have been derived.Based on observations made at the European Southern Observatory (La Silla/Chile)  相似文献   

9.
Well-determined physical parameters of 130 W Ursae Majoris (W UMa) systems were collected from the literature. Based on these data, the evolutionary status and dynamical evolution of W UMa systems are investigated. It is found that there is no evolutionary difference between W- and A-type systems in the   M – J   diagram, which is consistent with the results derived from the analysis of observed spectral type and of   M – R   and   M – L   diagrams of W UMa systems.   M – R   and   M – L   diagrams of W- and A-type systems indicate that a large amount of energy should be transferred from the more massive to the less massive component, so that they are not in thermal equilibrium and undergo thermal relaxation oscillation. Moreover, the distribution of angular momentum, together with the distribution of the mass ratio, suggests that the mass ratio of the observed W UMa systems decreases with decreasing total mass. This could be the result of the dynamical evolution of W UMa systems, which suffer angular momentum loss and mass loss as a result of the magnetic stellar wind. Consequently, the tidal instability forces these systems towards lower q values and finally to rapidly rotating single stars.  相似文献   

10.
We report on observations of the eclipsing binary 2MASS 19090585+4911585 with the 25 cm auxiliary telescope of the University Observatory Jena. We show that a nearby brighter star (2MASS 19090783+4912085) was previously misclassified as the eclipsing binary and find 2MASS 19090585+4911585 to be the true source of variation. We present photometric analysis of VRI light curves. The system is an overcontact binary of W UMa type with an orbital period of (0.288374 ± 0.000010) d (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

11.
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   

12.
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   

13.
We report the results of a search for variable stars in the open cluster NGC 2141. Ten variable stars are detected, among which nine are new variable stars and they are classified as three short-period W UMa-type eclipsing binaries, two EAtype eclipsing binaries, one EB-type eclipsing binary, one very short-period RS CVntype eclipsing binary, one d-type RR Lyrae variable star, and one unknown type of variable star. The membership and physical properties are discussed, based on their light curves, positions in the color magnitude diagrams, spatial locations and periods.A known EB-type eclipsing binary is also identified as a blue straggler candidate in the cluster. Furthermore, we find that all eclipsing contact binaries have prominent asymmetric eclipses and display the O'Connell effect, which increases with a decrease in orbital periods. This suggests that the O'Connell effect is probably related to the evolution of the orbital period in short period eclipsing binary systems.  相似文献   

14.
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   

15.
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   

16.
使用像管摄谱仪和Reticon探测器获得了食双星AA UMa的高色散和高时间分辨率的光谱,并用交叉相关函数法测得其视向速度。从光谱特征来看,AA UMa是一对W UMa型食双星。本文首次给出了AA UMa的分光轨道解。在圆周运动的假设下,轨道根数测定为:P=0.468171天;T_0(相应于测光主极小时刻)=HJD2,446,520.4448;K_1=124.0公里/秒;K_2=227.7公里/秒。像其他一些使用本方法获得分光轨道解的食双星一样,AA UMa系统的质心速度没有能够唯一地确定,但是V_0=-34.8公里/秒可能是一个较好的估值。根据分光轨道根数,本文给出了新的测光历元公式:HJD Min I=2,446,520,4448(8)+0.468171(48)·E。AA UMa两子星的光谱型十分相似,与变星总表(GCVS)所列的GoV相一致。两子星的质量比为0.54,星等差为0.36(～B)  相似文献   

17.
We used the Behlen observatory 0.76 m telescope and the CCD photometer to secure 689 observation of the eclipsing binary star KN Per. The observations were made on 8 nights during 1993 and 1994 with V and R bandpass filters. From 7 determinations of eclipse timings of minimum (V&R together), we have determined a new epoch and an orbital period of 0.8664604 days. The published spectral classification is A9. The 1993 version of the Wilson-Devinney model gave the photometric solutions. The adopted solution indicates that KN Per is a W UMa type contact binary. The mass ratio, q = (m2/m1, where star 1 eclipses at the primary minimum) = 0.23 suggests that KN Per is a W UMa system with A-type configuration. The secondary minimum shows a total eclipse. The asymmetry in the light curve is fitted with a cold spot on the secondary component of the system. The luminosity difference between the components is very large KN Per therefore, is most likely a single line spectroscopic binary. We recommend spectroscopic study of this system. Generally contact systems of spectral type A9 have periods ranging from 0.4 to 0.6 days. KN Per has considerably longer period and thus appears to be an evolved contact system with case B mass transfer. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

18.
The aim of this paper is to present a general method for computation of the geometrical elements of totally eclipsing W UMa (close, or in actual contact) binary systems in the frequency-domain.This method has been done using a new technique (two minima with the improved values of the photometric perturbation effects). The results are compared with the results calculated by different methods, that have used the same observation references.The improved photometric perturbation terms have been discussed and its effects are computed for both (primary and secondary) minima.  相似文献   

19.
This study presents an investigation of the orbital period variations of five Algol type binaries, UX Leo, RW Mon, EQ Ori, XZ UMa and AX Vul based on all available minima times. The O–C diagrams of all systems exhibit a periodic variation superimposed on a downward parabolic segment. The mass loss due to magnetic braking effect in the cooler components is assumed to account for the parabolic variation with a downward shape, while it is suggested that the light-time effect (LITE) due to an unseen component around the eclipsing binaries explains the tilted sinusoidal changes in their O–C diagrams. The orbital period decrease rates for the systems are estimated as approximately between about 0.7 and 2.5 s per century. It is clearly seen that mass loss effect is more dominant than the expected mass transfer for classical Algols in this study. The minimum mass of the probable third bodies around the eclipsing pairs was calculated to be ?0.5 M⊙ except for UX Leo, in which it was estimated to be approximately 0.9 M⊙. In order to search for third lights in the light curves of five systems, the V-light curves of the systems were analyzed and their physical and photometric parameters were determined. For UX Leo, a significant third light contribution was determined. We found a very small third light that can be tested using multi-color light curves, for RW Mon, EQ Ori and XZ UMa, while a third light for AX Vul could not be exposed.  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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