New photoelectric observations and light curve analysis of 44i bootis

The eclipsing binary 44i Boo was observed photoelectrically using the 40 cm Cassegrain telescope at the Al-Battani Observatory.The light curves were analysed using Fourier techniques of light changes in the frequency-domain, and new geometrical and physical elements have been obtained.A new active period to be started in 1986 has been observed.     

New techniques of light curve analysis: Application to V444 Cygni

A new method of light curve analysis is introduced for systems containing one component possessing an extended atmosphere. Occultation or partial eclipses may be treated with or without the presence of transparency effects. Besides admitting an arbitrary degree of transparency to the eclipsing component, an arbitrary law of limb-darkening may also be assigned to the eclipsed star. The method is applied to the analysis of continuum, narrow band light curves of V444 Cygni obtained by Cherepashchuk and Khaliullin. Primary and secondary minima are examined separately with reasonable results.     

The light curve analysis of MM Herculis

The photoelectric light curves of MM Her obtained in 1983 and 1984 by Evren (1985, 1987) were analyzed by two different methods. Firsly, the effects of the wave-like distortions on the observations were removed from the observed magnitudes by obtaining its mathematical expression. The remaining light curves were analyzed by using Wood's approach. Later, the light curves of the same years were treated by the method of Wilson-Devinney and distortions seen in the light curves were thought to be explained by locating the spots on the surface of the cooler component. The results obtained by two different approaches are in good agreement.     

New light curve analysis and period changes of the overcontact binary EQ Tauri

A photometric CCD study of EQ Tauris was carried out in the R, V and B bands. These new data were analyzed by using the PHOEBE and Binary Marker 3 programs, which yielded the geometrical system parameters and mass and radius of both stars. We find these to confirm the results of Pribulla and Vanko (2002). Using these new data together with data from the literature, the orbital period variations were studied by using the Kalimeris method. We find the same timescale of variability of the orbital period as Pribulla and Vanko (2002), namely about 49 years.     

New developments in eclipsing binary light curve modeling

The light curve modeling of binary stars has continued to evolve since its founding by Henry Norris Russell (see Russell and Merrill 1952 and citations therein) nearly a century ago, accelerated in the 1950s by Kopal's introduction of Roche geometry into models and by the development of synthetic light curve computer code in the 1970's. Improved physics and the use of more kinds of observational input are providing another round of important advances that promise to enlarge our knowledge of both binary stars and ensembles containing them. Here we discuss the newer horizons of light curve modeling and the steps being taken toward them.     

Light curve analysis of contact binaries: Characteristic quantities of the light curve

Quantities characterizing light curves of contact binaries of W UMa-type are introduced. For 2700 cases, theoretical light curves of contact binaries are computed by the light curve synthesis method, and characteristic quantities for these light curves are tabulated. An example of application of the table to the light curve analysis of contact binaries is shown, and the errors inherent in the solution are also discussed.     

BVRI photometry and light curve analysis of VW CEP

Synthetic light curve solutions for the W UMa-system VW Cep have been determined by applying the most new version of Wilson (1998)approach to B-observations of 1996 and VRI-observations of 1999. From a consideration of the possible evolution of this system, it is found that the system is a partial eclipsing contact one, and its primary to be a nearly Main-Sequence F5 star of mass 0.85 M _⊙ and the secondary to be a dwarf of spectral type G0 of mass 0.34 M _⊙. This revised version was published online in July 2006 with corrections to the Cover Date.     

Photometric observations and light curve analysis of ST Aquarii

The system of ST Aquarii has been observed inB andV filters at KOTTAMIA Observatory in Egypt. Two light curves have been obtained and new times of minima have been calculated.The light curves have been analysed using the theory of Fourier transform of light changes in frequencydomain, and new geometrical and physical elements have been obtained.     

Power spectrum analysis of the light curve of RR Tauri

Power spectrum analysis is applied to the light curve of RR Tauri. Periodicities are found at 80, 200 and 533 days with some variation in the peak positions and power for different decades. Factors involved in the classification of the variable are discussed.Receipt delayed by postal strike in Great Britain.     

1992 UBV observations of UV piscium and light curve analysis

In 1992 UBV photometry of short period binary system UV PSc were presented. The results obtained from the analysis ofU, B andV light curves represent transit solutions. The light fluctuations of out-side eclipses have been interpreted in terms of cool star-spots on the photosphere of the primary component. Its parameters have been determined.     

Photometric observation and light curve analysis of binary system ER-Orionis

Photometric observations of the over-contact binary ER ORI were performed during November 2007 and February to April 2008 with the 51 cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509 photomultiplier. We used these data to obtain the light curves and calculate the newtimes of minimum light in each filter and plot the O-C diagram of ER ORI. Using theWilson’s computer code with the help of an auxiliary computer program to improve the optimizations, the light curve analyses were carried out to find out the photometric elements of the system.     

An analysis of the spectra and light curve of Nova Centauri 1995

The light curve and spectra of Nova Centauri 1995 (V888 Cen) are analysed. The spectra were obtained a few days post-maximum. The nova is found to be a very fast nova, declining by 2 mag within about 5±2 d of maximum. The light curve shows strong oscillations in the transition region, of peak-to-peak amplitude about 1.5 mag and period 12–15 d. The light curve of Nova Centauri resembles closely that of Nova Aquilae 1918 (V603 Aql).
The early blue and red spectra obtained at Mt John show broad emission lines, many with P Cygni profiles. The absorption lines are found in two velocity systems at about −1765 and −3010 km s⁻¹, in respectively the principal and diffuse-enhanced stages of spectral development, as defined by McLaughlin. Nova Centauri has many Fe  ii lines in emission, indicating that it is a member of the Williams Fe  ii class of classical novae.     

Update on Comet Hartley-Good's light curve

Upto date light curve of Comet Hartley-Good (19851) is presented from middle of September 1985 to middle of January 1986. The light curve is based on all the existing observations reported in IAU circulars. When compared with the predicted light curve; shows active nature of the comet.     

New CCD photometry and light curve analysis of two WUMaBinaries: 1SWASP J133417.80+394314.4 and V2790 Orion

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.