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Öğe ABSOLUTE PROPERTIES OF THE ECCENTRIC ECLIPSING BINARY STAR FT ORIONIS(Iop Publishing Ltd, 2011) Sabby, Jeffrey A.; Lacy, Claud H. Sandberg; Ibanoglu, Cafer; Claret, AntonioAccurate absolute properties are determined for the first time for the 3.15 day period eccentric eclipsing binary star FT Ori based on new absolute photometry, five differential light curves, and a radial velocity curve. The stars appear to be normal for their spectral types, A0 + A2. The orbit is highly eccentric (e = 0.409) and shows apsidal motion with a period of 536 years. The absolute properties and the degree of central mass concentration of the stars are consistent with current theoretical models at an age of 190 Myr.Öğe Absolute properties of the neglected eclipsing B-type binary HD 194495(Elsevier Science Bv, 2012) Cakirli, Omur; Dervisoglu, Ahmet; Sipahi, Esin; Ibanoglu, CaferWe present the results of the high-resolution spectroscopic observations of the neglected binary system HD 194495 (B3 IV-V+B4 V). A combined analysis of three different photometric data set (Tycho B(T) and V(T) photometry, H(p)-band data of Hipparcos and V-band data of ASAS3 photometry) and radial velocities indicates that the system has an orbital period of 4.90494 +/- 0.00005 days and an inclination of 69 +/- 1 degrees. This solution yields masses and radii of M(1) = 7.57 +/- 0.08 M(circle dot) and R(1) = 5.82 +/- 0.03 R(circle dot) for the primary and M(2) = 5.46 +/- 0.09 M(circle dot) and R(2) = 3.14 +/- 0.08 R(circle dot) for the secondary. Based on the position of the two stars plotted on a theoretical H-R diagram, we find that the age of the system is greater than or similar to 28 Myr, according to stellar evolutionary models. The spectroscopic and photometric results are in agreement with those obtained using theoretical predictions. (C) 2011 Elsevier B.V. All rights reserved.Öğe The mass and radius of the M-dwarf companion in the double-lined eclipsing binary T-Cyg1-01385(Elsevier, 2013) Cakirli, Omur; Ibanoglu, Cafer; Sipahi, E.We observed spectroscopically the eclipsing binary system T-Cyg1-01385 in order to determine physical properties of the components. The double-lined nature of the system is revealed for the first time and the radial velocities are obtained for both stars. We have derived masses, radii and luminosities for both components. Analyzes of the radial velocities and the KeplerCam and the TrES light curves yielded masses of M-1 = 1.059 +/- 0.032 M-circle dot and M-2 = 0.342 +/- 0.017 M-circle dot and radii of R-1 = 1.989 +/- 0.022 R-circle dot and R-2 = 0.457 +/- 0.013 R-circle dot. Locations of the low-mass companion in the mass-radius and mass-effective temperature planes and comparison with the other low-mass stars show that the secondary star appears just at the transition from partially to fully convective interiors for the M dwarfs. When compared to stellar evolution models, the luminosities and effective temperatures of the components are consistent with Z = 0.004 and an age of about 6 Gyr. A distance to the system was calculated as d = 355 +/- 7 pc using the BV and JHK magnitudes. (C) 2013 Elsevier B.V. All rights reserved.Öğe Photometric and spectroscopic observations of the F3+M3 eclipsing binary T-Lyr0-08070(Elsevier, 2013) Cakirli, Omur; Ibanoglu, Cafer; Sipahi, E.The multi-color photometric and spectroscopic observations of the newly discovered eclipsing binary T-Lyr0-08070 were obtained. The resultant light and radial velocities were analysed and the absolute parameters of the components were determined. The system is composed of an F3 and an M3 main-sequence stars. Masses and radii were estimated to be 1.37 +/- 0.23 M and 1.60 +/- 0.09 R for the primary and 0.32 +/- 0.04 M. and 0.86 +/- 0.06 R. for the secondary star. The less massive secondary component has a radius at least two times larger with respect to its mass. Using the BVJHK magnitudes of the system we estimated an interstellar reddening of 0.22 mag and a distance to the system as 479 +/- 36 pc. (C) 2012 Elsevier B.V. All rights reserved.