• M. I. Nouh

      Articles written in Journal of Astrophysics and Astronomy

    • Relation between a function of the right ascension and the angular distance to the vertex for Hyades stars

      M. A. Sharaf M. I. Nouh A. S. Saad

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      In this paper, relation was developed for Hyades stars between a function of the right ascensions and the angular distances from the vertex. The precision criteria of this relation are very satisfactory and a correlation coefficient value of ≃ 1 was found which proves that the attributes are completely related linearly. The importance of this relation was illustrated through its usages as:

      •a criterion for membership of the cluster,

      •a generating function for evaluating some parameters of the cluster,

      •a generating function for the initial values of the vertex equatorial coordinates which could then be improved iteratively using the procedure of differential corrections.

    • On the Maximum Separation of Visual Binaries

      M. I. Nouh M. A. Sharaf

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      In this paper, an efficient algorithm is established for computing the maximum (minimum) angular separation ρmaxmin), the corresponding apparent position angles (𝜃|ρmax , 𝜃|ρmin) and the individual masses of visual binary systems. The algorithm uses Reed’s formulae (1984) for the masses, and a technique of one-dimensional unconstrained minimization, together with the solution of Kepler’s equation for (ρmax, 𝜃 |ρmax) and (ρmin, 𝜃 |ρmin). Iterative schemes of quadratic coverage up to any positive integer order are developed for the solution of Kepler’s equation. A sample of 110 systems is selected from the Sixth Catalog of Orbits (Hartkopf et al. 2001). Numerical studies are included and some important results are as follows:

      there is no dependence between ρmax and the spectral type and

      a minor modification of Giannuzzi’s (1989) formula for the upper limits of ρmax functions of spectral type of the primary.

    • Spectroscopic Analysis of the Eclipsing Binary ∝ CrB

      M. I. Nouh S. M. Saad B. Korany M. A. Elkhamisy

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      The eclipsing binary ∝ CrB, is a well-known double-lined spectroscopic binary. The system is considered unique among main-sequence systems with respect to its small mass ratio and large magnitude difference between the components. Our aim in the present paper is to compute the orbital parameters and to model the atmospheric parameters of the system. Synthetic spectral analysis of both the individual and disentangled spectra has been performed and yielded effective temperatures 𝑇eff = 10000 ± 250 K, surface gravities log 𝑔 = 4 ± 0.25 and projected rotational velocities 𝑣 sin 𝑖 = 110 ± 5 km/sec for the primary component, and 𝑇eff = 6000 ± 250 K and log 𝑔 = 4.5 ± 0.25 for the secondary component. Evolutionary state of the system is investigated using stellar models.

    • Light Curve Stability and Period Behavior of the Contact Binary TZ Boo

      M. M. Elkhateeb M. I. Nouh

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      New CCD observations of the eclipsing binary TZ Boo in BVR bands were carried out in 2006 (presented three new minima) and used together with all published minima to study and update the orbital period of the system TZ Boo by means of an (O–C) diagram. The period variation from 1926 to 2011 is represented by polynomial of eighth degree and indicates period variation of about 9.752 × 10-10 days/yr. We studied light curve stability over 85 yr covering all published observations in the V band and confirm the cyclic light curve variations.

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    • Continuous Article Publication

      Posted on January 27, 2016

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      Posted on July 25, 2019

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