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1.
In this paper, we give theBV photoelectric light curves of the Algol-type eclipsing binary EU Hydrae. We have analysed its period by means of the times of minima determined from this observation and the times of minima which other observers published. The period was found to gradually decrease with a change rate dP/dE = -3 . d 29 × 10–10. The obtained light curves have been solved using Wilson-Devinney's synthetic light-curve program. The results demonstrate that EU Hydrae is a detached system, the secondary component fills the Roche-lobe, its mass ratio is 0.205. EU Hya may evolve to be a semidetached system in which the secondary component fills the Roche-lobe.  相似文献   

2.
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   

3.
Photoelectric observations of VW Cephei in R and I bands were made from 1989 to 1992. 17 primary minima and 11 secondary minima were covered, it is found from the present observations that the period abruptly changed aboutl990 and the maxima I and II exchanged between 1992 and 1993.(Communicated by M. Kitamura)  相似文献   

4.
In order to get a satisfactory understanding of the periodic variation of the orbital period in the binary system HS Herculis, the study of this problem is resumed. Using recently observed primary and secondary minima, it is evident that after 1955 (E > -2000) the corresponding O – C diagram reflects the effect of apsidal motion. Any assumption on the presence of a third body is rejected, at least as long as the current aspect of the O–C diagram is concerned. For the interpretation of the sinusoidal period variation of the semi-detached system SW Cygni, 130 primary minima were compiled form the literature. Though it is considered as very likely that this variation of the period is primarily caused by apsidal motion, the hypothesis of a third body is analysed too. Further precise photometric and spectroscopic observations are recommended.  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.
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   

7.
UBV photometry of RS CVn-type eclipsing binary system ER Vulpeculae has been presented. The period comes out to be 0 . d 698093. The average depths of primary and secondary minima are, respectively, 0 . m 21 and 0 . m 12. The colours at various phases have been given. A dip is seen around phase 0 . p 73 as was seen in the observations of Arevaloet al. (1988). Large scatter is present in the observations as noticed earlier, and may be due to activity of the components.  相似文献   

8.
The W UMa system V758 Centauri has been observed photoelectrically in theUBV system at Bosque Alegre Station, and the comparison and check stars at Cerro Tololo Observatory. Full light curves were constructed from 1043 differentialUBV observations. A study of 11 photoelectric times of minimum light and of earlier photographic data shows that the period remained constant in the last century, V758 Cen shows a total occultation at secondary minimum, thus being an A-type W UMa system. Asymmetries are observed at primary minima whereas maxima are of different heights. Thermal decoupling of the components is suggested by the depth ratio of the minima; V758 Cen may be at the broken phase (or marginal contact) of a thermal relaxation oscillation.  相似文献   

9.
In 2003–2008, highly accurate photoelectric and CCD observations of the close binary system DI Her were performed in the V band. The light curves of three primary and three secondary eclipses were constructed. These observations, along with the highly accurate photoelectric observations of other authors obtained in different years from 1963 to 1986, have confirmed the difference between the observed (1 . o 3 ± 0 . o 1/100 yr) and theoretical (4 . o 3/100 yr) rates of apsidal motion. Our photometric data are indicative of a possible variability in the system with period P′ = 1.175 days and amplitude A′ = 0 . m 011, which is probably related to the pulsations of one of the components. There may be a third body in the system that produces in-phase variations in the times of primary and secondary minima with a period of 10.5 yr and an amplitude of 1 . m 5.  相似文献   

10.
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   

11.
DifferentialB-band photometry of BV Dra and BW Dra, obtained in 1965, is presented. Times of primary and secondary minima are derived and combined with published times for a period study. Period variations are found in both binaries and magnetic cycles are proposed as an explanation. The cycle length is 19 years in BV Dra and 8 years in BWDra On leave from Dyer Observatory, Vanderbilt University, Nashville, Tennessee.  相似文献   

12.
Detailed period study of the eclipsing binary system Delta Cap is presented. Available times of minima have been classified, and two minima have been found off the instant period trend. A new period of 1.d0227789 has been given. Period changes in different portions of the O?C diagram have been estimated, which range from 6.4×10?6 d to 1.8×10?3 d (?), the average being 3.5×10?5 d. A sinusoidal variation is evident in the O?C diagrams, which is indicative of the possible presence of a third body, having a period of nearly 62 years, however, it is yet to be confirmed.  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.
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   

15.
We consider a model of a young binary with a low-mass secondary component. Mass accretion from the remnants of the protostellar cloud onto the binary components is assumed to take place in accordance with current models; i.e., it proceeds mainly onto the low-mass component. The accretion is accompanied by mass outflow (disk wind), whose low-velocity component can be partially captured by the primary component. As a result, an asymmetric common envelope is formed. Its densest part is involved in the orbital motion of the secondary and can periodically shield the primary component of the binary from the observer. Assuming a standard dust-to-gas ratio for the disk wind (1: 100), we calculated the possible photometric effects from such eclipses and showed that they could be observed even at moderate accretion rates onto the low-mass binary component, ∼10−8–10−9 M ⊙ per year. In this case, the parameters of the minima depend on the model of the disk wind, on the ratio of its characteristic velocity to the orbital velocity of the secondary, and on its orbital inclination to the line of sight. These results can form the basis for interpreting a wide range of phenomena observed in young stars, such as the activity cycles in UX Ori stars, the unusually broad minima in some young eclipsing systems, etc., and for searching for substellar objects and massive protoplanets. In addition, the peripheral parts of the gas and dust disk around a young binary can fall within the shadow zone produced by the opaque part of the common envelope. In such cases, a shadow from the common envelope must be observed on the disk; this shadow must move over the disk following the orbital motion of the low-mass component. Detection and investigation of such structures in the images of protoplanetary disks may become a method of searching for protoplanets and studying binaries at early stages of their evolution.  相似文献   

16.
Many available published times of light minima of the active binary system UV Psc have been collected and analyzed using a new method proposed by Kalimeris et al. (1994). Similar to what was seen in other RS CVn-type binaries, the orbital period of UV Psc oscillates with a period of about 61 years and an semi-amplitude of 0.21 ×10-5 days. Two possible mechanisms (magnetic activity cycle mechanism and a light-time effect due to a hypothetical third body) that could modulated the orbital period behaviour are studied. We think that the cyclical period change in UV Psc can most probably be attributed to a magnetic activity cycle in the primary component. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

17.
The Behlen observatory 0.76 m telescope CCD photometer is used to obtain 347 observations of the short period (P0d.4) eclipsing binary star V719 Her. The observations done withV andR bandpass filters were made on 6 nights in 1993. Previously published light elements and the present five timings of minimum provide a new epoch and a more accurate orbital period of 0.4009828 days. Our analyses show that the period of the system appears to decrease. We recommend future monitoring of the eclipse minima for this system. No published spectral classification for V719 Her exists. From the color,V-R=0.391, we estimate it to be about F5.The 1993 version of the Wilson Devinney model gave the photometric solutions. The adopted solution indicates that V719 Her is a W UMa type contact binary. The mass ratio,q=(m 2/m 1, where star 1 eclipse at the primary minimum)=0.296 suggests that V719 Her is a WUMa system with type-A (transit during primary eclipse) configuration. The secondary minimum shows a total eclipse. V719 Her with period less than 0.5 and spectral class F5, is probably a zero-age contact system. Since our photometric solution shows that the luminosity difference between the components is very large, we suspect that V719 Her is most likely a single line spectroscopic binary. We recommend spectroscopic study of this system.  相似文献   

18.
The results from the simultaneous observations in B and R colours of AM Her are presented. Analysis of these data shows the following: (a) There are always two clear minima in the R light curves, while the secondary minimum in B light curves sometimes is not well defined; (b) The times of the minima in R and B colour nearly coincide; (c) The photometric period changes remarkably from cycle to cycle but its mean value remains constant; (d) Short stillstands on the increasing branches of the two minima are seen similar to those visible in UX UMa-type cataclysmic stars; (e) Besides the irregular flickering with time scale of a few minutes, a variability with a period 20.28 min in the two colours is established.  相似文献   

19.
The light outside the eclipses of the totally eclipsing RS CVn binary SV Camelopardalis (SV Cam) is Fourier analysed and the amplitudes of the distortion waves have been derived. The distribution of the percentage contributions of these amplitudes inV, B andU colours with respect to the luminosities of the binary components indicates that the hotter component is the source of the distortion waves. These distortion waves, attributed to star spots, are modelled according to Budding (1977) and spot parameters like longitude, latitude, temperature and size are obtained. From this study it is noticed that while symmetric waves with two minima could be fitted satisfactorily, asymmetric waves with more than two minima could not be fitted well. From the longitudes of the minima of the best fitted curves, migration periods of four spot groups are determined. Assuming synchronism between rotation and orbital periods, the rotation periods of the four spot groups are derived from their migration periods. The period of rotation of one of the spot groups having direct motion is found to be 0d.5934209 while the periods of the other three spot groups having retrograde motion are 0d.5926588, 0d.592607 and 0d.5924688. As the latitudes of these spots are known from modelling parameters, the latitude having a rotation period equal to that of the orbital period (co-rotating latitude) is found to be about 30°  相似文献   

20.
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   

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