X-ray warm absorber variability of the Seyfert Galaxy Arakelian 564

The aim of this paper is to study the variability of the warm absorber "clouds of ionised gas within AGN", for the Seyfert 1 galaxies Arakelian 564. The X-ray spectra for four XMM-Newton observations of this object are analysed in EPIC and RGS instruments. These four observations covered a period of eleven years. There are some changes in the ionisation parameter ($\xi$) of the absorbing matter from one observation to another( $\log\xi =0.889 \pm 3.11 \times 10^{-2}$ for year 2000 observation and $0.437 \pm 7.60 \times 10^{-2}$ for year 2001 ). Also the X-ray soft excess is studied for the four observation by using two blackbody parameters in EPIC spectra ( the first black-body temperature is $\sim$ $0.129 \pm 2.04 \times 10^{-3}$ Kev and the second is $\sim 1.74 \pm 7.6 \times {10^{-2}}$ Kev) and one black body parameter in RGS spectra

A Holistic Study of the W UMa Binary EQ Tau

We present a new BVR light curves of the system EQ Tau carried out in the period from March to April 2006 using a 50 cm F/8.4 Ritchey Chretien telescope of the Baja Astronomical Observatory (Hungary, and 512*512 Apogee AP-7 CCD camera). The observed light curves were analyzed using the 2009 version of the Wilson-Devinney code. The results show that the more massive component is hotter than the low massive one by 99 K. A long term orbital period study shows that the period increases by the rate 8.946*10^(-11) day/cycle. Evolutionary state of the system has been investigated and showed that, the primary component of the system is located nearly on the ZAMS for both the M-L and M-R relations. The secondary component is close to the TAMS track for M-L and above the M-R relations.Comment: 20 pages, 10 figures, 9 table

Light Curve Analysis of GSC 2750-0054 and GSC 03208-02644

We present the first photometric analysis for the newly discovered eclipsing binary systems of Algole-type GSC 2750-0054 and GSC 03208-02644. Our analysis was carried out by means of the most recent version of Wilson Devinney (WD) code, which applies the model atmosphere by Kurucz (1993) with prescription in pass band for the radiative treatment. The accepted light curve solutions reveal absolute physical parameters and the spectral classifications for the components are adopted. Distance to each system was calculated based on the parameters of the accepted photometric solutions. Comparison with the evolutionary models are presented.Comment: 11 pages, 6 figures, Submitted to New Astronom

Detailed ROSAT X-ray Analysis of the AM Her Cataclysmic Variable VV Pup

VV Pup is typical system of AM Her stars, where the main accreting pole rotates in and out of view during the orbital cycle. In the present paper we present ROSAT data analysis for the magnetic cataclysmic variable VV Pup. We obtained the X-ray light curves of VV Pup in high state, the PSPC count rate 0.1-2.0 keV is plotted as a function of time with bins of 10 sec and the count rate is folded over the orbital period of 100.4 min with bin size of 100 sec for individual observations. We calculate the mean best-fit PSPC spectrum, with a three-component spectral fit including a soft X-ray blackbody, hard X-ray bremsstrahlung, and Gaussian line covers the phase intervals, for a bright phase (phi_orb=0.9-1.1), the dip data (phi_orb=0.18-0.7), the egress from the dip (phi_orb=0.7-0.8), the phase interval phi = 0.1-0.18 and the mean best-fit spectrum for all data (phi_orb=0.0-1.0). We calculate spectral parameters, the hardness ratios, count rate and total integrated black body flux.Comment: 13 pages, 6 figure

Approximate solution to the fractional Lane-Emden type equations

In this paper, approximate solutions for a class of fractional Lane - Emden type equations based on the series expansion method are presented. Various examples are introduced and discussed. The recurrence relation for the components of the approximate solution is constructed. In the standard integer order derivative, it is shown that the results are the same as those obtained by Adomian decomposition method, homotopy perturbation method, modified Laplace decomposition method and variational iteration method

Spectroscopic Analysis of the Double Lined Eclipsing Binary {\alpha}Vir

{\alpha}Vir is a well known double-lined spectroscopic binary with a B-type for both components. In the present paper we have analyzed a total of 90 spectra obtained through 1992-2000. Spectral analysis are based on two spectral lines H(alpha) and HeI 6678 belong to H(alpha) region. Radial velocity analysis have suggested low eccentric orbit (e=0.002) at inclination (i=81.89+-2.34) and with 4d.01422 period, semi-amplitude k1=100 km/s, mass ratio q=0.49+-0.05 and mass function f(m) =0.547. Using KOREL program for spectrum disentangling we have been able to decompose the spectrum of the system to its primary and secondary components. Synthetic spectral analysis of both the individual and disentangled spectra has been performed and yielded effective temperatures Teff= 25000+-250 K, surface gravities log g=3.75+-0.25 and projected rotational velocities (v sin i= 180+-5 km/s) for the primary, while for the secondary they are Teff = 17000+-250 K, log g = 4.0+-0.25.Comment: 15 pages, 7 figures, 1 tabl

An Extensive Photometric Investigation of the W UMa System DK Cyg

DK Cyg (P = 0.4707) is a W Ursae Majoris type eclipsing binary system that undergoes complete eclipses. All the published photoelectric data have been collected and utilized to re-examine and update the period behavior of the system. A significant period increase with rate of 12.590x10-11 day/cycle was calculated. New period and ephemeris has been calculated for the system. A long term photometric solution study was performed and a light curve elements were calculated. We investigated the evolutionary status of the system using theoretical evolutionary models.Comment: 13 pages, 7 figures, 5 table

White Dwarf Stars as Polytropic Gas Spheres

Due to the highly degeneracy of electrons in white dwarf stars, we expect that the relativistic effects play very important role in these stars. In the present article, we study the properties of the condensed matter in white dwarfs using Newtonian and relativistic polytropic fluid sphere. Two polytropic indices (namely n=3 and n=1.5) are proposed to investigate the physical characteristics of the models. We solve the Lane-Emden equations numerically.. The results show that the relativistic effect is small in white dwarf stars.Comment: 5 figures, 1 table. arXiv admin note: text overlap with arXiv:astro-ph/0004317 by other author

Approximate Analytical Solutions to the Relativistic Isothermal Gas Spheres

In this paper, we introduce a novel analytical solution to Tolman-Oppenheimer-Volkoff (TOV) equation, which is ultimately a hydrostatic equilibrium equation derived from the general relativity in the framework of relativistic isothermal spheres. Application of the traditional power series expansions on solving TOV equation results in a limited physical range to the convergent power series solution. To improve the convergence radii of the obtained series solutions, a combination of the two techniques of Euler-Abel transformation and Pade approximation has done. The solutions are given in \exi-\theta and \exi-\mu phase planes taking into account the general relativistic effects \sigma= 0.1, 0.2 and 0.3. An Application to a neutron star has done. A Comparison between the results obtained by the suggested approach in the present paper and the numerical one indicates a good agreement with a maximum relative error of order 10-3, which establishes the validity and accuracy of the method. The procedure we have applied accelerated the power series solution with about ten times than of traditional one.Comment: 20 pages, 12 figure

Approximate Solution to the Fractional Second Type Lane-Emden Equation

The spherical isothermal Lane-Emden equation is a second order non-linear differential equation that model many configurations in astrophysics. In the present paper and based on the fractal index technique and the series expansion, the fractional lane-Emden equation involving modified Riemann-Liouville derivative is solved. The results indicate that, the series converges for the radius range with fractional parameter spreads over a wide range of the fractional parameter . Comparison with the numerical solution revealed a good agreement with a maximum relative error 0.05.Comment: 13 pages, 3 figure