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1.
We present an analysis of BV R light curves of an eclipsing binary CK Bootis, a system with a very small mass ratio. The light curves appear to exhibit a typical O'Connell effect. The light curves are analyzed by means of the latest version of the WD program. The asymmetry of the light curves is explained by a cool star spot model. The simultaneous BV R synthetic light curve analysis gives a tiny mass ratio of 0.12, an extremely large fill‐out factor of 0.65, and a very small difference between the component temperatures of 90 K. The absolute parameters of the system were also derived by combining the photometric solutions with the radial velocity data. The mass of the secondary is very low (0.15 M⊙) and it continues losing mass. Thirty seven new times of minimum are reported. It is found that the orbital period of the system has a quasi periodic variation, superimposed on a period increase. The long‐term period increase rate is deduced to be dP/dt = 3.54x10–7 d yr–1, which can be interpreted as being due to mass transfer from the less massive star to the more massive component. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

2.
Photometric BV light curves of BO CVn obtained in 1992 and new times of minima are presented. The primary minimum shows a transit, whereas the secondary minimum, shows an occultation. The system may be classified as an A‐type W UMa system. A complete study of minima allows one to detect a possibly increasing period by about 0.037 s/yr. This indicates that the conservative mass transfer rate from the less massive component to the more massive one is 1.57 10—10M⊙ /yr. Because of the variable period, the new ephemeris is determined for future observations. Using the Wilson‐Devinney code a simultaneous solution of the B and V light curves is also performed. The analysis shows that the system is in a contact configuration with q = 0.205 ± 0.001 and fillout factor (f) = 0.18, T1 = 7240 K (fixed), T2 = 7150± 10 K. The high orbital inclination i = 87°.54 ± 0.26 was con firmed by photometric observations of the secondary minimum.  相似文献   

3.
The photoelectric observations of the neglected binary AV Hya published by Srivastava and Kandpal (1980) have been re-analyzed using Wilson-Devinney's synthetic light-curve program. The binary turns out to be a near-contact semi-detached system. The primary, more massive, more luminous and greater component, eclipsed at primary minimum, is detached from its Roche lobe (85%). The secondary fills its Roche lobe and has a temperature difference of T=,-3414 K. As with other semi-detached binaries, the secondary is more evolved than that of the primary. Thetimes of light minima of the eclipsing have been analyzed,showing that the orbital period of AV Hya undergoes acontinuous decrease with a rate of dP/dE=-8.26×10-8 day/year. The mass transfer between the twocomponents can not explain the present orbital period variationsince the secondary component is filling the Roche lobe. Theorbital period change demonstrates that the system may undergoa secular mass and angular momentum loss and the system mayevolve from the present short-period near-contact system intoan A-type contact binary.  相似文献   

4.
New BV light curves and times of minimum light for the short period W UMa system LO And were analyzed to derive the preliminary physical parameters of the system. The light curves were obtained at Ankara University Observatory during 5 nights in 2003. A new ephemeris is determined for the times of primary minimum. The analysis of the light curves is made using the Wilson‐Devinney 2003 code. The present solution reveals that LO And has a photometric mass ratio q = 0.371 and is an A‐type contact binary. The period of the system is still increasing, which can be attributed to light‐time effect and mass transfer between the components. With the assumption of coplanar orbit of the third body the revealed mass is M3 = 0.21M⊙. If the period change dP/dt = 0.0212 sec/yr is caused only by the mass transfer between components (from the lighter component to the heavier) the calculated mass transfer rate is dm/dt = 1.682×10−7M⊙/yr. The absolute radii and masses estimated for the components, based on our photometric solution and the absolute parameters of the systems which have nearly same period are R1 = 1.30R⊙, R2 = 0.85R⊙, M1 = 1.31M⊙, M2 = 0.49M⊙ respectively for the primary and secondary components. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

5.
A new period (P=2 . d 9042997) of the eclipsing binary system VZ Hydrae has been given, which is based on all the available times of minima. The period based on the photoelectric epochs has also been presented. The O?C diagram and detailed period study of VZ Hya have been presented for the first time, and the period changes have been estimated in different portions of the O?C diagram. Significant period changes do not appear to have occurred in VZ Hya, however, the O?C diagram suggests that the period of the system shows a slow tendency to increase. Period changes of 10?5 d (?) to 10?7 d have occurred around the years 1933, 1971, and 1975. All four period changes are noted in the time-interval 1918 to 1978. Upward treands appear stronger than the declining trends. Secondary minima show larger fluctuations than the primary minima. The fluctuations of the O?C values around the zero-line of VZ Hya demands notice for searching out the cause of period variations such as the presence of a third body.  相似文献   

6.
On the basis of the published times of minima and our own observations, we analysed the period change of the Algol-type eclipsing binary CU Pegasi. Over almost seventy years of observations, the parabolic period change has been clearly seen as dP/dt = 1.38 × 10−6 d/year. The estimated mass transfer in the system is about 1 × 10−7 MM⊙/year.  相似文献   

7.
ST Carinae is an eclipsing binary with a period of 0 . d 90165 which is believed to consist of an A0V primary and a secondary of type F5-8IV. About 900 observations inUBV, made by Somerville in 1963 but unreduced at that time, are presented. The Wood model is used to obtain orbital elements, and four different solutions of the light curves are presented. These are also computed with the solutions obtained by previous investigators of this system. The solutions indicate a reasonably consistent geometry, but there is still substantial uncertainty with regard to the mass-ratio and dynamical status of ST Car. The possibility exists that ST Car is in the initial and rapid stage of mass exchange in which the primary component fills its Roche lobe and is losing mass to its companion. The two components of ST Car appear to be of normal dimensions, but additional work is needed to clarify the exact status of this system.  相似文献   

8.
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. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

9.
B andV photometry of DM UMa obtained between January, 1980 and June, 1984 is presented. Analysis yields a mean photometric period 7d.478±0d.010, compared to the known oribital period of 7d.492±0d.009. Light curves obtained during any two seasons do not agree in any of the following: shape, amplitude, phases of the light maxima and minima, mean light level, or brightness at the light maxima and minima. From the change inB-V over the photometric period, we concludethat the hemisphere visible during the light minimum is cooler than that seen during light maximum. The mean colorB-V=1m.065±0m.002 is consistent with K1 III or K2 IV. Phases of light minima lie on two well-separated groups with different slopes; the corresponding periods are 7d.471±0d.002 and 7d.481±0d.001, in dicating that both migrate linearly towards decreasing orbital phase. In terms of the starspot model this indicates that two respective centers of activity were situated at different longitudes and latitudes on a differentially rotating star. From circumstantial evidence we infer that the dark region seen from 1979 onwards disintegrated sometime between the 1982 and 1983 observing seasons, leaving behind an area of relatively high surface brightness. We can put a lower limit of about four years on the lifetime of a center of activity.  相似文献   

10.
The period study of the eclipsing binary system GH Pegasi has been presented for the first time. A new period (P=2d.556135) of GH Peg, based on all available times of minima, has been given. O–C diagrams of the system have also been presented for the first time, and the period changes present in the system have been analysed. The period shows changes around the year 1972 and 1981. The total period change in different portions of the O–C diagram, based on the corrected period, ranges from 5.2×10–6 d to 7.0×10–5 d. The photoelectric minima show sufficiently large scatter in the system.  相似文献   

11.
A new period (P=1 . d 533731) of the eclipsing binary system IT Persei has been given, which is based on all available times of minima. O-C diagrams of IT Persei, based on the period given in PPEN (1980) and based on the new period, have been given.Long-term period changes are not present in the system, however, some period fluctuations of the order of 10–5d are seen around the years 1907, 1921, and 1933.  相似文献   

12.
The Algol type eclipsing binary WX Eridani was observed on 21 nights with the 48-inch telescope of the Japal-Rangapur Observatory during 1973–74 and 1974–75 seasons in UBV colors. An improved period ofP=0d.82327038 was obtained from the analysis of the times of five primary minima. Standstills between phase angles 50–80°, 100–130°, 230–260° and 280–310° were present in the light curves. The analysis of the light curves indicated the eclipses to be grazing with the primary a transit and the secondary an occultation. Elements derived from the solution of the light curve using Russell-Merrill method are given. From the comparison of the fractional radii with Roche lobes, it is concluded that none of the components has filled its respective Roche lobe. The spectral type of the primary component is estimated to be F3 and it is found to be a -scuti type variable pulsating with two periods equal to one-fifth and one-sixth of the orbital period.  相似文献   

13.
It is shown that the erratic changes of the orbital period, which are observed in some detached eclipsing binary systems, cannot be interpreted as real if their light curves show changing anomalies with asymmetric minimum profiles. In this case the photometrically determined times of the minima do not coincide with the ideal geometric ones, which are unobservable. This fact and the applied reduction methods for deriving the photometric times of minima cause systematic period errors of cumulative character. The discussion of six photoelectrically-determined minima obtained within the last 20 yr, and earlier photographic ones of the 0d.479 period eclipsing binary XY UMa yields a constant period. The long cyclic light curve variations due to starspot activity of the larger and hotter component of this system are reflected in corresponding period oscillations. Dedicated to Dr. Ida Noddack on the occasion of her eightieth birthday.  相似文献   

14.
The orbital period variations of the Algol-type semidetached binary UW Vir are analyzed. It is shown that in addition to a long-term rapid increase (dP/dt = + 1.37 × 10−6 day/year), its orbit period has a variation with the period of 62.3 years. Based on the basic physical parameters given by Brancewicz and Dworak in 1980, the physical mechanisms causing the orbital period variations are investigated. The analysis indicates that the periodical variation of orbital period can be interpreted by the light-travel time effect due to the presence of a third body with the mass of M3 ≥ 0.94 M. As no observational information has been reported for this tertiary component, it might be a compact object (e.g., a white dwarf). The long-term increase of orbital period can be explained in terms of the mass transfer from the secondary to the primary component (dM2/dt = 1.43 × 10−7 M/year). This is in agreement with the semidetached configuration of the system with a lobe-filling secondary component. But according to the evolution theory of binaries, the Algol-type semidetached binary UW Vir should be at the evolutionary stage of slow mass transfer on the nuclear-reaction timescale of the secondary component. However, the analysis shows that the timescale for the periodical variation of orbital period is much shorter than the nuclear-reaction timescale of the secondary component, but close to the thermodynamic timescale of the secondary. This reveals that: (1) This binary system is at the evolutionary stage of rapid mass transfer on the thermodynamic timescale of the secondary component; or (2) The circumstellar matter of the system makes a contribution to the rapid increase of orbital period via the angular momentum transfer.  相似文献   

15.
New times of light minimum of the short‐period (P = 0d.26) close binary system, VZ Psc, are presented. A period investigation of the binary star, by combining the three new eclipse times with the others collected from the literatures, shows that the variation of the period might be in an alternate way. Under the hypothesis that the variation of the orbital period is cyclic, a period of 25 years and an amplitude of 0.d0030 for the cyclic change are determined. If this periodic variation is caused by the presence of a third body, the mass of the third body (m3) should be no less than 0.081M⊙. Since both components of VZ Psc are strong chromospherically active and the level of activity of the secondary component is higher than that of the primary one, the period may be more plausibly explained by cyclic magnetic activity of the less massive component. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

16.
In this work the light curves (LCs) solutions along with the radial velocity curve of the semidetached binary systemXZ And are presented using the PHOEBE program(ver 0.31a). Absolute parameters of the stellar components were then determined, enabling us to discuss structure and evolutionary status of the system. The analysis indicates that the primary is a non-synchronous (i.e., F1 = 3.50 ± 0.01) Main Sequence (MS) star and the secondary is a bit more evolved, and fills its Roche critical surface. In addition, times of minima data (“O ? C curve”) were analyzed. Apart from an almost parabolic variation in the general trend of O ? C data, which was attributed to a mass transfer from the secondary with the rate ?2 = (9.52 ± 0.41) × 10?10 M ⊙ yr?1; two cyclic variations with mean periods of 34.8 ± 2.4 and 23.3 ± 3.0 yr, modulating the orbital period, were found, which were attributed to a third body orbiting around the system, and magnetic activity cycle effect, respectively.  相似文献   

17.
The new period (P=0 . d 461700) of the eclipsing binary system DX Aqr has been presented, which is based on available times of minima. O–C diagram of DX Aqr has been presented for the first time, and the period variations present in the system have been analysed. In all five period increases and five period decreases are nothed, and four period increases and five period decreases have been discussed. The strongest period increase occurs between 1975 and 1976. The total period change in different portions of the O–C diagram ranges from 1.40×10–4 d to 3.61×10–6 d. Appreciable period fluctuations have been noted to have occurred in the time intervals, 1964–1965 and 1974–1975.  相似文献   

18.
The RS CVn-type eclipsing binary AR Lac has been observed in two colours,B andV, in 1978 and 1979. Several times of minima have been obtained during the observations and the new light elements have been calculated. The orbital period of the system was found to be decreasing with an amount of 14.6 s century–1.The light curves of the system obtained inB andV show a significant wave-like distortion outside eclipses. The amplitudes of the wave-like distortion inB andV are about 0 . m 09 and 0 . m 10 in 1978, and, 0 . m 12 and 0 . m 13 in 1979, respectively. The minima of the wave-like distortion have shifted with an amount of 0 . p 40 in one year, thus indicating the migration period of the wave-like distortion is about 2.5 yr.A noticeable variation of light during the totality of primary minimum has also been observed. This variation can be attributed to the distortion wave which has been moving towards decreasing phases.  相似文献   

19.
A first detailed period study of the eclipsing RS CVn-binary system RW Com is presented. A new period (P=0d.2373455) based on 223 minima is given. The O–C diagrams of RW Com have been presented for the first time. Types of ten minima have been corrected judging the period trend. Period changes in different portions of the O–C diagram (Figure 2) have been estimated. The total change in period (P/P) ranges from 5.5×10–7 to 6.4×10–6. Thus, P ranges from 1.3×10–7 d to 1.5×10–6 d. Numerous minima are available in the time interval 1967 to 1986. This part of the O–C diagram (Figure 2) shows a sinusoidal variation, thus, it is suspected that RW Com could be a three-body system. The period of variation due to third body appears to be nearly 16 years.  相似文献   

20.
The RS CVn-type eclipsing binary star MM Her has been observed in two colours,B andV, in 1979, 1980, and 1983. Several minima times were obtained during the observations and new light elements calculated. The light curves of the system obtained in blue and yellow lights show a significant wave-like distortion which migrates towards the decreasing orbital phases. Its migration period was estimated to be about 3.5 yr. The amplitudes of the wave-like distortion inB andV appear to change each year. The primary minimum of the system is a total eclipse with a duration of 0d.08.  相似文献   

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