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  • 1
    Electronic Resource
    Electronic Resource
    The photometric observations of ER vulpeculae: photometric analysis with the W-D code (1995)
    Springer
    Astrophysics and space science 234 (1995), S. 271-280 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The photometric observations of ER Vul were obtained in UBV light in 1994, at Birouni Observatory, University of Shiraz, Iran. The three light curves, which are almost complete, have been analyzed separately by means of Wilson and Devinney method (1971). The light curves include proximity effects, wave-like distortions, mutual eclipses, and short term light fluctuations. The appropriate value of the mass ratio of this system was found after extensive searches. ER Vul has a detached configuration where the two components are very nearly fill their Roche lobe. ER Vul has the characteristic of a RS CVn type system. The absolute dimensions for the primary and secondary of this system were calculated from its spectral types and by combining the photometric solution with inferred component radial velocities (Northcott and Bakos, 1967).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00627672
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  • 2
    Electronic Resource
    Electronic Resource
    A reanalysis of the light curve of RT Persei with the W-D code (1996)
    Springer
    Astrophysics and space science 243 (1996), S. 275-283 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The UBV photometric observations of RT Per, from Sanwal and Chaubey (1981), were analyzed by the Wilson and Devinney code (1971). The light curves include reflection effects that for the first time has been suggested by Dugan (1911). RT Per has a semi-detached configuration where the lower-mass component is in contact with its respective Roche surface. The higher-mass component very nearly fills its Roche lobe. It has the characteristic of an Algol type system. The absolute dimensions for the primary and secondary of this system were calculated from its spectral types and by combining the photometric solution with inferred component radial velocities (Lu, 1990).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00644700
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of the light curves of RT Persei by automatized fourier techniques (1978)
    Springer
    Astrophysics and space science 58 (1978), S. 3-19 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new method has been developed by Kopal (1977c, Paper XII) to make use of expressions for the fractional loss of light α 0 l of the arbitrarily limb-darkened stars in the form of Hankel transforms of zero-order, in order to evaluate the explicit forms of the α 0 l ′s for different types of eclipse, as well as of the momentsA 2m of the respective light curves in a closed form. The automated method has been tested successfully on the light curves of RT Persei. Also, a photometric curve fit of RT Persei is investigated by application of numerical quadratures to determine the theoretical light curve appropriate for the Roche model. Finally a comparative discussion is given of various methods of light curve analaysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645372
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  • 4
    Electronic Resource
    Electronic Resource
    Fourier analysis of the light curves of eclipsing variables, XXII (1978)
    Springer
    Astrophysics and space science 59 (1978), S. 333-345 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The theoretical values of the momentsA 2m for any type of eclipses, expressed in terms of the elementsL 1,a andc 0, have been derived in the simple forms of rapidly convergent expansions to the series of Chebyshev polynomials, Jacobi polynomials and KopalJ-integrals (Kopal, 1977c) and hold good for any real (not necessarily integral) value ofm≥0. The aim of the present paper has been to establish explicit expressions for the Jacobian and its fast enough computation in the light changes of close eclipsing systems, arising from the partial derivative of different pairs ofg-functions (Kopal and Demircan, 1978, Paper XIV) with respect toa andc 0 2 , for any type of eclipses (be these occultations or transit, partial, total or annular) and for any arbitrary degreel of the adopted law of limb-darkening. The functional behaviour of this Jacobian would determine the reasonable light curve in connection with geometrical determinacy of the parametersa andc 0. In the expansion of Jacobian, the terms consist of two polynomials which satisfy certain three-term recursion relations having the eclipse parametersa andc 0, as their arguments. Closed form expressions forf-functions, as well as of the Jacobian (e.g.,m=1, 2, 3), obtaining in the case of total eclipses, are given for a comparative discussion with the theoretical values of Jacobian derived from partial derivative of different pairs ofg-functions. The numerical magnitude of Jacobian would determine the best combination of the momentsA 2m in the different pairs ofg-functions and definite results would follow in the subsequent paper of this series (Edalati, 1978c, Paper XXIV).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01023923
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  • 5
    Electronic Resource
    Electronic Resource
    Fourier analysis of the light curves of eclipsing variables, XXIII (1978)
    Springer
    Astrophysics and space science 59 (1978), S. 431-441 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The method of evaluating the photometric perturbationsB 2m of eclipsing variables in the frequency domain, developed by Kopal (1959, 1975e, 1978) for an interpretation of mutual eclipses in systems whose components are distorted by axial rotation and mutual tidal action. The aim of the present paper has been to establish explicit expressions for the photometric perturbationB 2m in such systems, regardless of the kind of eclipses and non-integral values ofm. Recently, Kopal (1978) introduced two different kinds of integrals with respect to associated α-functions andI-integrals which have been expressed in terms of certain general types of series that can be easily programmed for automatic computation within seconds of real time on highspeed computers. Following a brief introduction (Section 1) in which the need of this new approach will be expounded, in Section 3 we shall deduce the integral $$\int_0^{\theta \prime } {\tfrac{{\alpha _n^\prime }}{\delta }} d(sin^{2m} \theta )$$ in terms of a certain general type of series and also β-function, which should enable us to evaluate explicit expressions forf * (h) ,f 1 (h) ,f 2 (h) as well asB 2m .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01023929
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  • 6
    Electronic Resource
    Electronic Resource
    Fourier analysis of the light curves of eclipsing variables, XXIV (1978)
    Springer
    Astrophysics and space science 59 (1978), S. 443-462 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The aim of the present paper will be to evaluate numerically Jacobian and other functions which have been discussed in more detail in a previous paper of this series (Edalati, 1978b, Paper XXII), and also choose the most convenient moments to obtain a good determination for the unknown eclipse parametersa andc 0. More than 12 different pairs ofg-functions for real values ofm have been investigated numerically and diagrammatically. The behaviour ofg-functions depends but very little on different combination of the moments, and related diagrams are approximately the same asg 2 andg 4 (Kopal and Demircan, 1978, Paper XIV). The behaviour of the vanishing Jacobian, arising from different pairs ofg-functions for real values ofm⪌1 has been shown diagrammatically in terms ofa andc 0. Accordingly, we obtain the optimum combination of the moments (i.e.,A 6,A 7,A 8 andA 9) ing-functionsg 7 andg 8. It has been noted that the behaviour of theg-functions which depend on the combinations of the higher order moments (i.e.,m≥5) have been ruled out, because the proportional error of the momentsA 2m increases with increasing values of realm. The automated method has been tested successfully on the light curve of RT Per (Mancusoet al., 1977; Edalati, 1978a). Finally, a comparison is given of the elements of RT Per arising from two different pairs ofg-functions, i.e.,g 2,g 4 (Edalati, 1978a) andg 7,g 8 for the light curves analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01023930
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  • 7
    Electronic Resource
    Electronic Resource
    Fourier analysis of the light curves of eclipsing variables XVII: The photometric perturbations (1978)
    Springer
    Astrophysics and space science 57 (1978), S. 181-190 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Values of the photometric perturbations $$\mathfrak{P}_{2m} $$ required in the frequency-domain analysis for the accurate determination of parameters characterizing stars in eclipsing binary systems when some degree of ‘proximity effect’ complications are present in the light curves are tabulated, corresponding to a wide range of such parameters. The relative smallness of the perturbation values permit a rapidly convergent iterative approach to the final parameter specification. Also, in view of the relative smallness, linear interpolation from the table over a wider range of nontabulated parameters should be effective in assessing the effects of the perturbations in a general case. The illustrative application to the light curve of RT Per appears to confirm this.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00639054
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  • 8
    Electronic Resource
    Electronic Resource
    Almost-contact semidetached EP Cep in NGC 188 (1994)
    Springer
    Astrophysics and space science 220 (1994), S. 107-113 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The photomectic observations of EP Cep, from Kaluzny and shara (1987), were analyzed by the Wilson and Devinney method. The appropriate value of the mass ratio of this system was found after extensive searches. EP Cep has a semi-detached configuration where the lower-mass component is in contact with its respective Roche surface. The higher-mass component very nearly fills its Roche lobe. It is very close to being a critical configuration. The mass ratio of the system is about 1.292 and the inclination is 66 . ° 942. EP Cep has the characteristic of a W-type WUMa system. The absolute dimensions for the primary and secondary of this system were calculated from its spectral types and by combining the photometric solution with inferred component radial velocities (Baliunas and Guinan, 1985).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00628081
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  • 9
    Electronic Resource
    Electronic Resource
    An analysis of the optical light curve of the X-ray binary 3U 1653+35 (1989)
    Springer
    Astrophysics and space science 151 (1989), S. 181-207 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The purpose of this paper is to provide an estimate of several parameters of X-ray binary system 3U 1653+35, based a study of the optical light curve of the companion of HZ Her. The introductory section gives a general outline of the problem and deals with the general method of estimation of the parameters. In Section 2, the reflection effect in close binary systems is demonstrated in the end of this section we first introduce a new method of evaluation of reflection effect in close binary systems. Section 3 gives an analysis of the optical curve of the X-ray binary system 3U 1653+35, and general discussion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00648378
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  • 10
    Electronic Resource
    Electronic Resource
    Photoelectric observations of 44i Boo (BD+48°2259) (1989)
    Springer
    Astrophysics and space science 152 (1989), S. 89-104 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The observations of the eclipsing binary 44i Boo was made in 1978 Biruni Observatory, Shiraz, Iran. The filters used were the standard Strömgrenuvby filters. The comparison star during the observations was 47 k i Boo (BD+48°2262). All differential atmospheric extinction effects were then removed in the reduction process. The variable (44i Boo) and the comparison stars are very close to each other, so that the extinction corrections were insignificant. Following an introductory section about a description of the stellar type and the properties of the photoelectric light curve of 44i Boo will be set third. Section 2 will contain the technique of observation with the telescope for obtaining data points, and also phase determination of the time of observations. Section 3 will give the reduction of the data points, and in reducing the charts, we have to determine the time for the mid-point of each fluctuation for each filter and its deflection, and eventially we have suggested two methods for reducing the charts. Section 4 will outline some requiring steps for running the computer programme, and then from the computer output, we obtain the light curve of the programme star. It is inclosed the final light curves of 44i Boo for filtersu, v, b, andy by this paper. An analysis of the light curves of 44i Boo will introduce in the frequency domain (Kopal, 1977; Edalati, 1978) in a subsequent paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00645989
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