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1.
Photoelectric observations of the RS CVn type non-eclipsing binary UX Arietis obtained at Nizamiah Observatory during the observing seasons of 1975–76, 1981–82 and 1982–83 are presented. The light curve of UX Ari showed a distortion wave with an amplitude inV varying from 0.02 mag during 1975–76 to 0.15 mag during 1982–83. An analysis of the available data shows that the light maximum is almost constant. It is also evident that the light-curve minimum decreases as the wave amplitude increases. The constant light at maximum,V = 6.51 ± 0.03 indicates the unspotted photospheric brightness. It is also suggested that the variation in meanV brightness is mainly due to spot activity and not due to intrinsic variation.  相似文献   

2.
Two-colour photoelectric observations of LX Per carried out at Ege University Observatory in 1981 and 1982 observing seasons are presented. The light curve of the system has a wave-like distortion which migrates towards the decreasing orbital phase. The period of the retrograde migration of the wave-like distortion has been determined as 475 days. The amplitude of the wave appears to change with time periodically.  相似文献   

3.
We report results of the first five observing campaigns for the open stellar cluster NGC 7243 in the frame of project Young Exoplanet Transit Initiative (YETI). The project focuses on the monitoring of young and nearby stellar clusters, with the aim to detect young transiting exoplanets and to study other variability phenomena on time‐scales from minutes to years. After five observing campaigns and additional observations during 2013 and 2014, a clear and repeating transit‐like signal was detected in the light curve of J221550.6+495611. Furthermore, we detected and analysed 37 new eclipsing binary stars in the studied region. The best fit parameters and light curves of all systems are given. Finally, we detected and analysed 26 new, presumably pulsating variable stars in the studied region. The follow‐up investigation of these objects, including spectroscopic measurements of the exoplanet candidate, is currently planned. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

4.
Between 1981 February and 1984 April we had four observing sessions on the dwarf cepheid HD 94033, After examining observational data gathered over a period of 10 years, we found that its O-C showed periodic variations. A study of these variations led us to conclude that HD 94033 may be a binary system.  相似文献   

5.
The double-lined spectroscopic and eclipsing binary ER Vul was observed in blue and yellow light during the 1984 and 1985 observing seasons. In 1984 four and in 1985 three different light curves in each colour were obtained. The system sometimes is too active and sometimes too quite. The wave-like distortion has been obtained for each light curve and a period of migration has been estimated to be about 8–9 months. The light fluctuations, which are the main characteristics of ER Vul, seems to be related with the wave minimum, (e.g., spotted regions) of the component(s).  相似文献   

6.
A detailed two colour (BV) photoelectric photometry of the late-type eclipsing binary AD BOO was carried out in 1981 April–May. We found its period to be 2.0688112 d, double what was thought previously. The light curve outside the eclipses is basically flat with Irregular fluctuations of ˜0.075 mag. It is basically an Algol-type curve, with a principal minimum of 0.65 mag and a secondary minimum of 0.40 mag. The O-C diagram of the minimum epoch shows that the period has tended to increase. The photometric solution by the classical Russel-Merrill method gives k = 0.786. The principal minimum corresponds to a partial eclipse of the transit type.  相似文献   

7.
New BV photoelectric observations of the W UMa-type system V508 Ophiuchi, made in 1986 at the Kryonerion Astronomical Center of the National Observatory of Athens, Greece, are given. The corresponding mean light curves, as well as those obtained in 1981 at the same station using the same instruments, are analysed using frequency-domain techniques. The geometrical and photometric elements of the system have been found. These are combined with the now available spectroscopic data of the system to get its absolute elements. A general discussion for the light variations between the old and the new observations is made. From the light curve analysis it was found that V508 Oph is an A-type W UMa binary with both of its components to fill their corresponding Roche lobes.  相似文献   

8.
A total of 704 previously published photoelectricB colour observations of the multiple system HR 4560 are analyzed by means of the light curve models NDE (Popper and Etzel, 1981) and WINK (Wood, 1972) in an iterative procedure. As a result, we have found that componentC of the multiplpe system ADS 8347 is the most probable origin of the observed eclipses. Some relevant astrophysical parameters of the component stars which indicate a normal Main-Sequence binary star have also been estimated.  相似文献   

9.
For the variable binary AM Herculis, which is the proto-type of a subgroup of cataclysmic stars, results from the study of long-term behaviour are given. The following part of the publication concerns the observation series, the long-term light curve and the orbital light changes. On the base of 1275 photographic observations in B, V and U, most of B, covering the time interval between the years 1982 and 1991 new statements can be made about the common photometric behaviour of the star, its low and high states and the mutual correlations between them, the individual influences of the orbital light changes superimposed to the total brighhtness and last but not least about the colour behaviour of the star within these individual occurrences and the whole time interval, which is object of the second part of this study.  相似文献   

10.
We obtained several epochs of light minima and a complete R light curve of the W-type contact binary V1128 Tau in 2009. Two cool spots on the massive component are used to model the photometric light curve. Using all available data we find evidence for a long-term period variation with an amplitude of 0.0050±0.0012 days and a period of 16.7±0.9 years. Using parameters derived from a photometric model of the 2009 light curve we show that this period change could be explained by the Applegate mechanism on one of the components.  相似文献   

11.
Two-colour light curves of Z Her were obtained observing the system from 1978 to 1981. The wave-like distortion at outside eclipses were derived. The amplitudes of the wave increase and its minimum migrates towards the decreasing orbital phase with a period of about 1.4 yr. An attempt was made to represent the wave-like distortions with a truncated Fourier series. The representation was found to be unsatisfactory since the distribution of the present observations is not regular but forms separate groups along the time axis. Therefore, further observations to cover the phases evenly in between the minima are needed.  相似文献   

12.
We report a ～6.1 yr quasi-periodicity for the blazar S5 0716+714 using the radio light curves at 4.8, 8 and 14.5 GHz observed by the University of Michigan Radio Astronomical Observatory (UMRAO) from 1981 to 2012, by means of the Jurkevich, discrete correlation function (DCF) and power spectral analysis techniques. There are a general correlation among light curves at different frequencies and a time lag of \(170\pm 10\) days between 4.8 and 14.5 GHz light curves can be confirmed. We also estimate the orbit parameters assuming a binary black hole system, and the magnetic field strength under the jet comoving frame.  相似文献   

13.
The eclipsing binary UV Piscium was observed with the standardUBV filters during 1976-77, 1977-78 and 1978-79 observing seasons with the 1.22-m reflecting telescope of the Japal-Rangapur Observatory. A wave-like distortion on the light curve noticed by Carr (1969), Oliver (1974), Sadik (1979) and Zeiliket al. (1982a) is confirmed by the present observations. Combining our observations with those of Carr, Oliver and Sadik, it is found that the distortion wave is moving towards decreasing orbital phase with a period of about 1200 days. The source of the observed distortion wave is found to be the hotter component.  相似文献   

14.
This paper presents a new CCD Bessell VRcIc light curves and photometric analysis of the newly discovered RS CVn type eclipsing binary star V1034 Her. The light curves were obtained at the Çanakkale Onsekiz Mart University Observatory in 2006. Variations of the orbital period of the system were firstly studied. The (O − C) diagram with a low range of observing time of about 20 years shows an upward parabola, which indicates a secular increase in the orbital period of the system. The light curves are generally those of detached eclipsing binaries; however, there are large asymmetries between maxima. The VRcIc light curves were analysed with two different fitting procedures: Wilson–Devinney method supplemented with a Monte Carlo type algorithm and Information Limit Optimization Technique (ILOT). Our general results find V1034 Her. as a well detached system, in which the components are filling 65% of their Roche lobes. Light curve asymmetries of the system are explained in terms of large dark starspots on the primary component. The primary star shows a long-lived spot distribution with active longitudes in the same hemisphere.  相似文献   

15.
We present optical photometry of the short period eclipsing RS CVn system, UV Piscium for the years 1966–1984. After removing the spot effects from the light curves of Vivekananda Rao and Sarma (1981), we analyzed the cleaned data to obtain system parameters. For each light curve, we model the distortion waves in order to study the behaviour of star spots in this system. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
This paper gives the result of photographic photography of the central star AGK3-0° 695 of the planetary nebula NGC 2346 made from 1981 through 1987. From it we see that after the large-amplitude eclipses which had started at the end of 1981 had continued for several years, the amplitude began to decrease rapidly in 1986 to ˜1.1 mag from ˜4 mag in 1984. In 1987, only irregular fluctuations with amplitudes ˜0.4 mag were present in the light curve and not longer any clear periodicity. A preliminary analysis of this phenomenon is carried out here.  相似文献   

17.
The variation of the specific intensity across the stellar disc is an essential input parameter in surface brightness reconstruction techniques such as Doppler imaging, where the relative intensity contributions of different surface elements are important in detecting star-spots. We use phoenix and atlas model atmospheres to model light curves derived from high precision (signal-to-noise ratio ≃ 5000) Hubble Space Telescope ( HST ) data of the eclipsing binary SV Cam (F9V+K4V), where the variation of specific intensity across the stellar disc will determine the contact points of the binary system light curve. For the first time, we use χ2 comparison fits to the first derivative profiles to determine the best-fitting model atmosphere. We show the wavelength dependence of the limb darkening and that the first derivative profile is sensitive to the limb-darkening profile very close to the limb of the primary star. It is concluded that there is only a marginal difference (<1σ) between the χ2 comparison fits of the two model atmospheres to the HST light curve at all wavelengths. The usefulness of the second derivative of the light curve for measuring the sharpness of the primary's limb is investigated, but we find that the data are too noisy to permit a quantitative analysis.  相似文献   

18.
UW CrB (MS 1603+2600) is a peculiar short-period X-ray binary that exhibits extraordinary optical behaviour. The shape of the optical light curve of the system changes drastically from night to night, without any changes in overall brightness. Here we report X-ray observations of UW CrB obtained with XMM–Newton . We find evidence for several X-ray bursts, confirming a neutron star primary. This considerably strengthens the case that UW CrB is an accretion disc corona system located at a distance of at least 5–7 kpc (3–5 kpc above the Galactic plane). The X-ray and Optical Monitor (ultraviolet–optical) light curves show remarkable shape variation from one observing run to another, which we suggest are due to large-scale variations in the accretion disc shape resulting from a warp that periodically obscures the optical and soft X-ray emission. This is also supported by the changes in phase-resolved X-ray spectra.  相似文献   

19.
BP Vulpeculae is a bright eclipsing binary system showing apsidal motion. It was found in an earlier study that it shows retrograde apsidal motion which contradicts theory. In this paper we present the first BV light curve of the system and its light curve solution as well as seven new times of the minima from the years 1959–1963. This way we could expanded the baseline of the investigation to five decades. Based on this longer baseline we concluded that the apsidal motion is prograde agreeing with the theoretical expectations and its period is about 365 years and the determined internal structure constant is close to the theoretically expected one.  相似文献   

20.
We present new CCD photometric observations of V1044 Her obtained on May 22, 23 and 24, 2015. From our data, we derived five new light curve minimum times. Combining our new results with previously available CCD light minimum times, we derived an updated ephemeris and discovered that the period of this binary system exhibits an oscillation. The cyclic variation may be caused by the light-time effect via the presence of a third body or magnetic activity cycle. We calculated the corresponding period of the third body to be 14.1 ± 1.4 years or magnetic cycle to be 12.2 ± 0.7 years. We analyzed our new asymmetric light curves to obtain photometric solutions and starspot parameters using the Wilson and Devinney program. The final results show that V1044 Her is a contact binary system with a degree of contact factor f = 3.220( ± 0.002)%.  相似文献   

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