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Öğe Analysis of light curves and apsidal motion of neglected southern eclipsing binary V399 Pup(Elsevier Science Bv, 2014) Bulut, I.; Bulut, A.; Cicek, C.In this study, the Hipparcos and ASAS light curves of the eclipsing binary V399 Pup have been analyzed using the Wilson-Devinney program. The light curve analyses have found that V399 Pup is a detached binary system with eccentric orbit. The apsidal motion parameters of the system have been obtained from the O-C curve analyses. The system has been revealed to have an orbital eccentricity of e = 0.145 +/- 0.006, the apsidal motion rate has been obtained omega = 0.0385 +/- 0.0069 deg cycle(-1), and it corresponds to an apsidal motion period of U = 100.2 +/- 18.0 years. (C) 2014 Elsevier B.V. All rights reserved.Öğe Apsidal Motion in Eclipsing Binaries: FT Ori and MZ Lac(Amer Inst Physics, 2016) Bulut, A.; Bulut, I.; Cicek, C.; Erdem, A.In this study, the apsidal motion analysis of two eccentric eclipsing binaries, FT Ori (P = 3.150 days, e = 0.397) and MZ Lac (P = 3.158 days, e = 0.399), have been presented. Their O - C diagrams were studied using all reliable times of minima found in the literature and new values for the elements of the apsidal motion for two systems have been computed. We found long periods of apsidal motion of 538 +/- 12 years and 424 +/- 6 years for FT Ori and MZ Lac, respectively.Öğe Apsidal Motion of Two Eclipsing Binaries: V796 Cyg and V2783 Ori(Amer Inst Physics, 2017) Bulut, A.; Bulut, I.; Cicek, C.; Erdem, A.In this study, the orbital period variations of two eclipsing binary systems showing apsidal motion were studied. Their O - C diagrams were analysed using all reliable eclipse timings and the elements of apsidal motion of two systems were improved. We found periods of apsidal motion of V796 Cyg and V2783 Ori to be 32.7 +/- 0.2 years and 415 +/- 50 years, respectively.Öğe CCD photometric analysis of the W UMa-type binary V376 Andromeda(Elsevier Science Bv, 2011) Cicek, C.This study presents the absolute parameters of the contact binary system V376 And. CCD photometric observations were made at the canakkale Onsekiz Mart University Observatory in 2004. The instrumental magnitudes of all observed stars were converted into standard magnitudes. New BV light curves of the system were analysed using the Wilson-Devinney method supplemented with a Monte Carlo type algorithm. Since there are large asymmetries between maxima (i.e., O'Connell effect) in these light curves, two different models (one with a cool spot and one with a hot spot) were applied to the photometric data. The best fit, which was obtained with a large hot spot on the secondary component, gives V376 And as an A sub-type contact binary in poor thermal contact and a small value of the filling factor (f approximate to 0.07). Combining the solutions of our light curves and Rucinski et al. (2001)'s radial velocity curves, the following absolute parameters of the components were determined: M(1) = 2.44 +/- 0.04 M(circle dot), M(2) = 0.74 +/- 0.03 M(circle dot), = 2.60 +/- 0.03 R(circle dot), R(2) = 1.51 +/- 0.02 R(circle dot), L(1) = 40 +/- 4 L(circle dot) and L(2) = 5 +/- 1 L(circle dot). We also discuss the evolution of the system, which appears to have an age of 1.6 Gyr. The distance to V376 And was calculated as 230 +/- 20 pc from this analysis, taking into account interstellar extinction. (c) 2010 Elsevier B.V. All rights reserved.Öğe Cool Active Binaries Recently Studied in the CAAM Stellar Program(Astronomical Soc Pacific, 2010) Cicek, C.; Erdem, A.; Soydugan, Faruk; Dogru, D.; Ozkardes, B.; Erkan, N.; Budding, E.We summarize recent work on cool active stars in our programme. We carried out photometry at the canakkale Onsekiz Mart University (COMU) observatory, and high-resolution spectroscopy at Mt John University Observatory, as well as collecting data from other facilties. A combination of analysis methods, including our information limit optimization technique (ILOT) with physically realistic fitting functions, as well as other public-domain software packages, have been used to find reliable parameters. Stars in our recent programme include V1430 Aql, VI 034 Her, V340 Gem, SAO 62042, FI Cnc, V2075 Cyg, FG UMa and BM CVn. Light variations, sometimes over numerous consecutive cycles, were analysed. For AB Dor and CF Tuc, we compared broadband (B and V) maculation effects with emission features in the Ca II K and H-alpha lines. Broadband light curves typically show one or two outstanding maculae. These appear correlated with the main chromospheric activity sites ('faculae'), that occur at similar latitudes and with comparable size to the photometric umbrae, but sometimes with significant displacements in longitude. The possibility of large-scale bipolar surface structure is considered, keeping in mind solar analogies. Such optical work forms part of broader multiwavelength studies, involving X-ray and microwave observations, also mentioned.Öğe Discovery of new variable stars at the Canakkale Onsekiz Mart University Observatory(Astronomical Soc Pacific, 2007) Bakis, V.; Bakis, H.; Demircan, O.; Budding, E.; Erdem, A.; Cicek, C.We present the light curves of five variable stars discovered at the Canakkale Onsekiz Mart University Observatory. From the light curve shapes of the variables we see that GSC 4288 0186 and GSC 4019 3345 are detached, USNO 1500-00409928 is a W UMa-type eclipsing binary, while the others seem to be intrinsic variable stars. By using a 30-cm telescope equipped with an ST237 CCD camera dedicated for times of minima observations, we plan to perform systematic observations to discover new variable stars with the help of automatic data reduction techniques in the future.Öğe First ground-based photometry and light-curve analysis of the eccentric eclipsing binary V744 Cas(Wiley-V C H Verlag Gmbh, 2006) Bulut, I.; Cicek, C.; Erdem, A.; Bakis, V.; Demircan, O.; Degirmenci, O. L.The first ground-based BVR photometric observations of the recently discovered eclipsing binary V744 Cas are presented. From these measurements, timings for two primary and one secondary minima have been calculated. The light curves of the system were analyzed by using the Wilson-Devinney program. The analysis shows that the system is detached with two similar components of spectral type A2V, and the orbit is eccentric (e = 0.0662 +/- 0.0005). The longitude of the periastron (w) was found significantly different for two different light curves (ours and that of Hipparcos), which is strongly suggestive of an apsidal motion with a period of about 425 +/- 68 yr. This makes V744 Cas an important candidate for studies of apsidal motions. The first estimate of the absolute dimensions place the system close to the terminal age of the main sequence (TAMS) in the HR diagram. The distance from the spectroscopic parallax (d = 740 +/- 10 pc) was found to be slightly larger than the Hipparcos distance of d = 610 +/- 400 pc. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Öğe Light Curve Analysis of Southern Eclipsing Binary EM Car(Amer Inst Physics, 2017) Cicek, C.; Bulut, I.; Bulut, A.In this study, ASAS light curve of the eclipsing binary EM Car (Sp = O8V, P = 3.4 days) has been analyzed using the Wilson-Devinney method. The light curve analyses have found that EM Car is a detached eclipsing binary system with small eccentric orbitÖğe Light-Time Effect in Two Eclipsing Binaries: NO Vul and EW Lyr(Amer Inst Physics, 2017) Bulut, A.; Bulut, I.; Cicek, C.; Erdem, A.In this study, orbital period variations of two eclipsing binary systems (NO Vul and EW Lyr) were discussed. Possible light time effects due to third bodies in these systems were re-examined. The mass function and orbital period of hypothetical third bodies were calculated to be 0.000627 +/- 1.000003 M-circle dot, 26.17 +/- 0.05 years and 0.12682 +/- 0.00003 M-circle dot, 77.23 +/- 0.72 years for NO Vul and EW Lyr, respectively.Öğe New Discovered Pulsational Components in Algol Type Binaries and their Positions on the plane of Porb-Ppuls(Astronomical Soc Pacific, 2010) Soydugan, Esin; Soydugan, Faruk; Senyuz, T.; Tuysuz, M.; Bakis, V.; Bilir, S.; Cicek, C.In this study, eclipsing binaries located in the delta Scuti region of the instability strip were chosen from the list of candidate eclipsing binary systems with delta Scuti components. These candidate systems were photometrically observed and some of them were announced to be new Algol-type binaries with delta Scuti components. Although the pulsational variability could not be determined for some of the candidate Algols, pulsational components in EW Boo and DY Aqr have been discovered for the first time. The light curves of EW Boo and DY Aqr were analyzed to model the variations caused by the eclipsing behavior and then we determined the pulsational periods and amplitudes of the pulsating components in these Algols. The relationship between the pulsation and orbital periods of the eclipsing binaries were tested and discussed for the cases of EW Boo and DY Aqr.Öğe Period Changes in Two Contact Binaries: V700 Cyg and PY Lyr(Amer Inst Physics, 2016) Bulut, A.; Bulut, I.; Cicek, C.; Erdem, A.In this paper, orbital period variations of these two contact binaries (V700 Cyg and PY Lyr) were studied. O-C diagrams of these binaries were analyzed with the least-squares method by using all available times of minima. Apparent period changes of these two contact binaries were explained in terms of light-time effect due to a third body. Masses of third bodies were found to be 0.014 +/- 0.001 M-circle dot and 0.130 +/- 0.006 M-circle dot for V700 Cyg and PY Lyr, respectively.Öğe Period studies of classical Algol-type binaries II: UX Leo, RW Mon, EQ Ori, XZ UMa and AX Vul(Elsevier Science Bv, 2011) Soydugan, Faruk; Erdem, A.; Dogru, S. S.; Alicavus, F.; Soydugan, Esin; Cicek, C.; Demircan, O.This study presents an investigation of the orbital period variations of five Algol type binaries, UX Leo, RW Mon, EQ Ori, XZ UMa and AX Vul based on all available minima times. The O-C diagrams of all systems exhibit a periodic variation superimposed on a downward parabolic segment. The mass loss due to magnetic braking effect in the cooler components is assumed to account for the parabolic variation with a downward shape, while it is suggested that the light-time effect (LITE) due to an unseen component around the eclipsing binaries explains the tilted sinusoidal changes in their O-C diagrams. The orbital period decrease rates for the systems are estimated as approximately between about 0.7 and 2.5 s per century. It is clearly seen that mass loss effect is more dominant than the expected mass transfer for classical Algols in this study. The minimum mass of the probable third bodies around the eclipsing pairs was calculated to be <= 0.5 M-circle dot, except for UX Leo, in which it was estimated to be approximately 0.9 M-circle dot. In order to search for third lights in the light curves of five systems, the V-light curves of the systems were analyzed and their physical and photometric parameters were determined. For UX Leo, a significant third light contribution was determined. We found a very small third light that can be tested using multi-color light curves, for RW Mon, EQ On and XZ UMa, while a third light for AX Vul could not be exposed. (C) 2010 Elsevier B.V. All rights reserved.Öğe Period studies of five neglected Algol-type binaries: RW Cet, BO Gem, DG Lac, SW Oph and WY Per(Elsevier Science Bv, 2010) Erdem, A.; Dogru, S. S.; Soydugan, Faruk; Cicek, C.; Demircan, O.We investigated the orbital period variations of five neglected Algol-type eclipsing binaries (RW Cet, BO Gem, DG Lac, SW Oph and WY Per) in this study Their O-C diagrams display tilted sinusoidal variations superimposed on upward parabolic forms The parabolic variations, which correspond to secular period increases, were interpreted in terms of the combined effect of mass transfer and loss Then, the mass transfer rates from the less massive secondary components to more massive primaries for non-conservative cases were calculated to be similar to 10(-7) M(circle dot)/yr for RW Cet. DG Lac and SW Oph and similar to 10(8) M(circle dot)/yr for BO Gem and WY Per The tilted (eccentric) sinusoidal representations of the O-C variations were interpreted in terms of the light-time effect due to unseen components in the systems. The possible third bodies in four Algol binaries (excluding RW Cet) would have masses larger than one solar mass If these hypothetical large massive third bodies were normal stars, they should be detectable Therefore, new astrometric, photometric and spectroscopic observations of these systems and careful analyses of the resulting data are required (C) 2010 Elsevier B V All rights reservedÖğe SX Aurigae: A close binary at the early stage of contact phase(Elsevier Science Bv, 2014) Ozturk, O.; Soydugan, Faruk; Cicek, C.This study presents analysis of new multi-band light curves of beta Lyrae-type eclipsing binary SX Aur. Radial velocities of both components of the system were collected from the literature and simultaneous light curve solutions made to determine the properties of the system and absolute elements of its components. The derived masses and radii of the components are M-1 = 11.3 +/- 0.2 M-circle dot, M-2 = 6.9 +/- 0.1 R-1 = 5.32 +/- 0.02 R-circle dot and R-2 = 4.23 +/- 0.03.R-circle dot, while the distance of the system is estimated at 1220 +/- 75 pc. It was found that SX Aur is a shallow-contact binary and thus may be in the stage between beta Lyrae and W UMa-type binaries. From O-C based period analysis of SX Aur, it is seen that the period of the system increases at a rate of 0.0055 s yr(-1). The most plausible physical mechanism for this period variation is non-conservative mass transfer from the secondary to the primary component at a rate of 3.13 x 10(-7) M-circle dot yr(-1). (c) 2014 Elsevier B.V. All rights reserved.Öğe The detached eclipsing binary TX Her revisited(Elsevier, 2011) Erdem, A.; Alicavus, F.; Soydugan, Faruk; Dogru, S. S.; Soydugan, Esin; Cicek, C.; Demircan, O.This paper presents new CCD Bessell BVRI light curves and photometric analysis of the Algol-type binary star TX Her. The CCD observations were carried out at Canakkale Onsekiz Mart University Observatory in 2010. New BVRI light curves from this study and radial velocity curves from Popper (1970) were solved simultaneously using modern light and radial velocity curves synthesis methods. The general results show that TX Her is a well-detached eclipsing binary, however, both component stars fill at least half of their Roche lobes. A significant third light contribution to the total light of the system could not be determined. Using O-C residuals formed by the updated minima times, an orbital period study of the system was performed. It was confirmed that the tilted sinusoidal O-C variation corresponds to an apparent period variation caused by the light travel time effect due to an unseen third body. The following absolute parameters of the components were derived: M-1 = 1.62 +/- 0.04 M-circle dot, M-2 = 1.45 +/- 0.03 M-circle dot, R-1 = 1.69 +/- 0.03 R-circle dot, R-2 = 1.43 +/- 0.03 R-circle dot, L-1 = 8.21 +/- 0.90 L-circle dot, and L-2 = 3.64 +/- 0.60 L-circle dot. The distance to TX Her was calculated as 155 +/- 10 pc, taking into account interstellar extinction. The position of the components of TX Her in the HR diagram are also discussed. The components are young stars with an age of similar to 500 Myr. (C) 2011 Elsevier B.V. All rights reserved.Öğe The first BVR light curves and period analysis of the eclipsing binary V821 Cas(Elsevier Science Bv, 2007) Degirmenci, O. L.; Bozkurt, Z.; Yakut, K.; Demircan, O.; Erdem, A.; Cicek, C.; Bulut, I.The first BVR light curves of the eclipsing binary V821 Cas are used to derive the physical parameters of the system. The light curves were obtained during 2000 and 2001 observational seasons at Ege University Observatory (EUO). Period variation of the system was also investigated. For the first time apsidal motion elements of the system were obtained from the O-C curve analyses. Preliminary absolute parameters of the components were computed taking into account the results of light curves analysis. Observational and theoretical internal structure constants were estimated to be log (k) over bar (2obs) = -2.66 and log (k) over bar (2,theo) = -2.42, respectively.(c) 2006 Elsevier B.V. All rights reserved.Öğe The Light Curve Analysis of The Highly Eccentric Eclipsing Binary KIC 10296163(Amer Inst Physics, 2019) Cicek, C.; Bulut, A.; Bulut, IIn this study, the analysis of the Kepler light curve of the eclipsing binary KIC 10296163 (Gaia DR2 2085670964017513856, R.A.(2000) = 19(h)564(m)40(s).07, DEC2000 = +47(0) 21'21 ''.97, m(R) = 13.43 mag) is presented. The light curve of the system shows a secondary minimum from a shifted phase 0.5 which indicates the ellipticity of the orbit. By using the PHOEBE program we analysed the light curve to achieve the orbital parameters of the system. The results of our analysis indicates a detached system where the orbit is highly eccentric (e = 0.357 +/- 0.003). Therefore, KIC 11858541 is a suitable candidate for apsidal motion studies.Öğe Third Body Effects in The Period Changes of Two Algol Binaries: V342 Aql and TW Lac(Amer Inst Physics, 2017) Cicek, C.; Bulut, I.; Bulut, A.The O - C diagrams of two Algol-type eclipsing binaries V342 Aql and TW Lac have been analyzed with the least-squares method by using all available minima times. The period changes in their O - C diagrams have been discussed with respect to the Light-Time Effect (LITE) that originates from gravitational influence of a third body. New LITE elements, orbital periods and possible minimum masses of third bodies are given.
