Photometric study of the short period W UMa system VW Cephei (original) (raw)

A photometric light variation and a 1500 days secondary period in the W UMa system TZ bootis

Astrophysics and Space Science, 1989

Photoelectric observations of the eclipsing variable TZ Bootis, obtained in 1983 and 1986, in the two colours B and V are presented. They are compared with the previous light curves of the system. The light curve changes show that the system TZ Bootis has a solar-like activity cycle with a period of 1500 days. The primary shows a transit, whereas the secondary shows an occultation minima. The maxima exhibit a large difference suggesting a large complication in the system. The (O-C) trend indicates that the period did not remain constant; a satisfactory representation of all the observed time of minimum light was obtained assuming a linear trend in the (O-C)s. The star may be classified to A-type W UMa systems.

Photometry of the VV Cephei stars

1993

Abstract: Photometric UBVRI and UBVRIJHL observations of 17 VV Cep stars were carried out from the end of 1989 to the beginning of 1993. For six of the stars, this was the first UBVRI photometry ever. The mean brightness level of the objects studied was found to be the same as that observed at the end of the 1960s. The observed features of the star PZ Cas were analyzed, and they were found to be more typical of binary systems of the VV Cep type than of isolated M supergiants. Observational data for NS Vul were considered, and these indicate that its components may not be physically related. Article: Introduction VV Cep stars are binary systems consisting of an M supergiant and a hot dwarf or giant, which is, as a rule, of spectral type B. These stars were identified by Bidetman (1954) via their spectra, which have multiple Fell emission lines in addition to TiO absorption bands. VV Cep stars were described in detail in Cowley's survey (1969), which mentions 13 objects of this t...

First photometric study of W UMa-type binary systems: BK Vul and V699 Cep

New Astronomy, 2024

In this study, new CCD photometric observations and photometric analysis of BK Vul and V699 Cep systems, which are classified as contact binaries in the literature, are presented. For the V699 Cep, the TESS light curve was also used in the photometric analysis. We determined the basic astrophysical parameters of the BK Vul and V699 Cep systems from photometric analysis using the Wilson-Devinney method. Due to the lack of spectroscopic data for both systems in the literature, these absolute parameters were approximately calculated as to be 2 = 0.73 ⊙ , 1 = 1.39 ⊙ and 2 = 1.09 ⊙ for BK Vul, and 2 = 0.36 ⊙ , 1 = 2.40 ⊙ and 2 = 1.33 ⊙ for V699 Cep after estimating the mass of the primary component. The period decrease rate (dP/dt) and cyclic variation period of BK Vul were determined from the − analysis as-3.86 ×10 −7 day yr −1 and 27 yrs., respectively. The evolutionary status of components of both systems were discussed.

uvby − β PHOTOELECTRIC PHOTOMETRY OF CEPHEID STARS

Revista Mexicana de Astronomía y Astrofísica, 2010

We present time-series uvby − β photometry of 41 classical Cepheid stars. A brief discussion of a comparison between the present data and previous photometric observations is included.

Light curve modeling of the short-period W UMa star GSC 02049-01164

Proceedings of the International Astronomical Union, 2015

The preliminary results of an analysis of the time-series photometric data of binary star GSC 02049-01164 (ROTSE1 J164341.65+251748.1) are presented. GSC 02049-01164 was observed for eight consecutive nights with the 0.84-m telescope of the San Pedro Martir Observatory in Mexico. The light curve of GSC 02049-01164 is typical of those of W UMa type binary stars. In an effort to gain a better understanding of the binary system and determine its physical properties we have analyzed the light curve with the software PHOEBE V.0 0.31a. We have found that GSC 02049-01164 binary system has a mass ratio of ~ 0.42, an inclination of ~ 85 degrees, a semi-major axis of ~ 2.24 R ⊙. It is likely that the two stellar components are in contact, with a degree of overcontact of 13%. The physical parameters of the stellar components have been derived.

UBV photoelectric observations of the eclipsing binary system XZ Cep

Astrophysics, 2010

Results of the three-colour photoelectric observation of the close binary system XZ Cep, obtained at the Abastumani Astrophysical observatory, are presented. XZ Cep (BD+66 o 1512) is double-lines spectroscopic system consisting of late O and early B star. It was discovered by Schneller [1], who determined the type of variability and photometric elements. The history of photometric observations and their interpretations can be found in Glazunova and Karetnikov [2]. Giuricin et al [3] performed a light-curve analysis using the B and V photometry of Harvig [4]. Since the mass ratio was not determined at the time of their study, they examined several solutions for different mass ratios and concluded that the observations were best satisfied by the model in which the primary (brighter) component filled the Roche lobe. Mass can be transferred from the brighter component to the smaller detached secondary component, which is probably heavier. A later photometric study of XZ Cep by Antokhina and Kumsiashvili [5] in which new UBV photoelectric observations were presented, used a spectroscopic mass ratio (M 2 /M 1) of 0.78 Glazunova [6]. Modern methods of synthesis of the theoretical light curves of close binary systems were used. The solution complies with the following model: the main the brighter but less massive component (M 2 =14.2M☉) fills or nearly fills its own Roche lobe (μ 1~1), temperature t 2 =22 500 K. The second, more massive component (M 1 =18.1M☉) is far from filling the Roche lobe (μ 2~0 .65) and has temperature t 1 =31 600 K. In the main minimum, it is totally eclipsed by the brighter component. We note that there is no contradiction that the deeper minimum corresponds to the eclipse of the fainter star. Since the temperature of the companion is higher, there is a considerable affect of "reflection" from the side of the main component facing it. In the minimum of brightness the main component is towards us by its other cooler side, that is, the star M 1 and the hotter side of M 2 are eclipsed. We note that in the phases 0.35-0.40, 0.6-0.9 the theoretical light curves do not quite agree with the observations. This is obviously due to the influence of gaseous flows in the system, observed in these phases (Fig. 1). These light-curves were analyzed again by Harries et al. [7] who also obtained a new radialvelocity curve of this system. Harries et al. confirmed that the system is a semidetached one and the cooler, less massive component is filling its critical Roche lobe.

Analysis of the activity of the eclipsing binary WZ Cephei

Astronomy & Astrophysics Supplement Series, 1998

The present study deals with the problem of the orbital and physical parameters' estimation of the ac- tive eclipsing binary WZ Cep based on the interpretation of its photometric observations. The B and V light curves (Homann 1984), as well as the new ones obtained at the Maidanak Observatory in the B, V and R passbands dur- ing 1995, are analysed and discussed. These two groups of light curves show large dierences in their shape and in the depth of the primary minimum. Homann's light curves show big asymmetry, especially conspicuous in the dierent height of the successive maxima. The new obser- vations give light curves that are almost symmetric having signicantly shallower primary minimum. They are analysed in the framework of the Roche computer model (Djura sevi c 1992a) by applying the inverse problem method (Djura sevi c 1992b) based on Marquardt's (1963) algorithm. The model is generalised for the case of an overcontact conguration also. To ex- plain these light cu...

Time series analysis of V 368 Cephei photometry

Astronomy & Astrophysics, 1999

Our time series analysis of V 368 Cep photometry ascertains the rotation period of 2. d 74 uniquely. The manifestations of starspot induced luminosity variations in this chromospherically active star include rapid light curve changes and differential rotation of about 3%. We conclude that the single rapidly rotating variable V 368 Cep is a high inclination K1v post T Tauri star.

A Photometric Study of the Active Ew/RS Binary Star System: GSC 05586-00371

Open European Journal on Variable Stars, 2022

GSC 05586-00371 is a fast-rotating (Prot ≈ 0.44 days) eclipsing binary. Our study showed that this star system is an overcontact eclipsing binary star that belongs to the W UMa class with characteristics of RS CVn type stars. We studied this binary system by photometric means through the V and I bandpass where data by the ASAS-SN survey have also been utilized. our photometry yielded a more precise orbital period that was obtained on its discovery. ASAS-SN data over a 6-year period revealed a long-term photometric wave that is attributed to star spot activity. We monitored the binary system over a 73-hour monitoring period to detect any possible flares from the system, where two consecutive events were monitored from one of our observing stations. Through the use of the Wilson-Devinney program as applied by Binary Maker 3.0, we have obtained a model for this binary system that reveals the presence of star spots on both components. Our results show that the star spot activity is rather dynamic where their influence on the system's light output changed on seasonal timescales.